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Sample records for african cichlid radiations

  1. The genomic substrate for adaptive radiation in African cichlid fish

    OpenAIRE

    Brawand, David; Russell, Pamela

    2014-01-01

    Cichlid fishes are famous for large, diverse and replicated adaptive radiations in the Great Lakes of East Africa. To understand the molecular mechanisms underlying cichlid phenotypic diversity, we sequenced the genomes and transcriptomes of five lineages of African cichlids: the Nile tilapia (Oreochromis niloticus), an ancestral lineage with low diversity; and four members of the East African lineage: Neolamprologus brichardi/pulcher (older radiation, Lake Tanganyika), Metriaclima zebra (rec...

  2. Evolution of genomic structural variation and genomic architecture in the adaptive radiations of African cichlid fishes

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    Shaohua eFan

    2014-06-01

    Full Text Available African cichlid fishes are an ideal system for studying explosive rates of speciation and the origin of diversity in adaptive radiation. Within the last few million years, more than 2000 species have evolved in the Great Lakes of East Africa, the largest adaptive radiation in vertebrates. These young species show spectacular diversity in their coloration, morphology and behavior. However, little is known about the genomic basis of this astonishing diversity. Recently, five African cichlid genomes were sequenced, including that of the Nile tilapia (Oreochromis niloticus, a basal and only relatively moderately diversified lineage, and the genomes of four representative endemic species of the adaptive radiations, Neolamprologus brichardi, Astatotilapia burtoni, Metriaclima zebra, and Pundamila nyererei. Using the tilapia genome as the reference genome, we generated a high-resolution genomic variation map, consisting of single nucleotide polymorphisms (SNPs, short insertions and deletions (indels, inversions and deletions. In total, around 18.8, 17.7, 17.0 and 17.0 million SNPs, 2.3, 2.2, 1.4 and 1.9 million indels, 262, 306, 162, and 154 inversions, and 3509, 2705, 2710 and 2634 deletions were inferred to have evolved in the N. brichardi, A. burtoni, P. nyererei and M. zebra respectively. Many of these variations affected the annotated gene regions in the genome. Different patterns of genetic variation were detected during the adaptive radiation of African cichlid fishes. For SNPs, the highest rate of evolution was detected in the common ancestor of N. brichardi, A. burtoni, P. nyererei and M. zebra. However, for the evolution of inversions and deletions, we found that the rates at the terminal taxa are substantially higher than the rates at the ancestral lineages. The high-resolution map provides an ideal opportunity to understand the genomic bases of the adaptive radiation of African cichlid fishes.

  3. Testing the stages model in the adaptive radiation of cichlid fishes in East African Lake Tanganyika.

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    Muschick, Moritz; Nosil, Patrik; Roesti, Marius; Dittmann, Marie Theres; Harmon, Luke; Salzburger, Walter

    2014-11-22

    Adaptive radiation (AR) is a key process in the origin of organismal diversity. However, the evolution of trait disparity in connection with ecological specialization is still poorly understood. Available models for vertebrate ARs predict that diversification occurs in the form of temporal stages driven by different selective forces. Here, we investigate the AR of cichlid fishes in East African Lake Tanganyika and use macroevolutionary model fitting to evaluate whether diversification happened in temporal stages. Six trait complexes, for which we also provide evidence of their adaptiveness, are analysed with comparative methods: body shape, pharyngeal jaw shape, gill raker traits, gut length, brain weight and body coloration. Overall, we do not find strong evidence for the 'stages model' of AR. However, our results suggest that trophic traits diversify earlier than traits implicated in macrohabitat adaptation and that sexual communication traits (i.e. coloration) diversify late in the radiation. PMID:25274371

  4. Bentho-Pelagic Divergence of Cichlid Feeding Architecture Was Prodigious and Consistent during Multiple Adaptive Radiations within African Rift-Lakes

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    W. James Cooper; Kevin Parsons; Alyssa McIntyre; Brittany Kern; Alana McGee-Moore; R. Craig Albertson

    2010-01-01

    Background How particular changes in functional morphology can repeatedly promote ecological diversification is an active area of evolutionary investigation. The African rift-lake cichlids offer a calibrated time series of the most dramatic adaptive radiations of vertebrate trophic morphology yet described, and the replicate nature of these events provides a unique opportunity to test whether common changes in functional morphology have repeatedly facilitated their ecological success. ...

  5. Bentho-pelagic divergence of cichlid feeding architecture was prodigious and consistent during multiple adaptive radiations within African rift-lakes.

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    W James Cooper

    Full Text Available BACKGROUND: How particular changes in functional morphology can repeatedly promote ecological diversification is an active area of evolutionary investigation. The African rift-lake cichlids offer a calibrated time series of the most dramatic adaptive radiations of vertebrate trophic morphology yet described, and the replicate nature of these events provides a unique opportunity to test whether common changes in functional morphology have repeatedly facilitated their ecological success. METHODOLOGY/PRINCIPAL FINDINGS: Specimens from 87 genera of cichlid fishes endemic to Lakes Tanganyka, Malawi and Victoria were dissected in order to examine the functional morphology of cichlid feeding. We quantified shape using geometric morphometrics and compared patterns of morphological diversity using a series of analytical tests. The primary axes of divergence were conserved among all three radiations, and the most prevalent changes involved the size of the preorbital region of the skull. Even the fishes from the youngest of these lakes (Victoria, which exhibit the lowest amount of skull shape disparity, have undergone extensive preorbital evolution relative to other craniofacial traits. Such changes have large effects on feeding biomechanics, and can promote expansion into a wide array of niches along a bentho-pelagic ecomorphological axis. CONCLUSIONS/SIGNIFICANCE: Here we show that specific changes in trophic anatomy have evolved repeatedly in the African rift lakes, and our results suggest that simple morphological alterations that have large ecological consequences are likely to constitute critical components of adaptive radiations in functional morphology. Such shifts may precede more complex shape changes as lineages diversify into unoccupied niches. The data presented here, combined with observations of other fish lineages, suggest that the preorbital region represents an evolutionary module that can respond quickly to natural selection when fishes

  6. Annotation of expressed sequence tags for the East African cichlid fish Astatotilapia burtoni and evolutionary analyses of cichlid ORFs

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    Braasch Ingo

    2008-02-01

    Full Text Available Abstract Background The cichlid fishes in general, and the exceptionally diverse East African haplochromine cichlids in particular, are famous examples of adaptive radiation and explosive speciation. Here we report the collection and annotation of more than 12,000 expressed sequence tags (ESTs generated from three different cDNA libraries obtained from the East African haplochromine cichlid species Astatotilapia burtoni and Metriaclima zebra. Results We first annotated more than 12,000 newly generated cichlid ESTs using the Gene Ontology classification system. For evolutionary analyses, we combined these ESTs with all available sequence data for haplochromine cichlids, which resulted in a total of more than 45,000 ESTs. The ESTs represent a broad range of molecular functions and biological processes. We compared the haplochromine ESTs to sequence data from those available for other fish model systems such as pufferfish (Takifugu rubripes and Tetraodon nigroviridis, trout, and zebrafish. We characterized genes that show a faster or slower rate of base substitutions in haplochromine cichlids compared to other fish species, as this is indicative of a relaxed or reinforced selection regime. Four of these genes showed the signature of positive selection as revealed by calculating Ka/Ks ratios. Conclusion About 22% of the surveyed ESTs were found to have cichlid specific rate differences suggesting that these genes might play a role in lineage specific characteristics of cichlids. We also conclude that the four genes with a Ka/Ks ratio greater than one appear as good candidate genes for further work on the genetic basis of evolutionary success of haplochromine cichlid fishes.

  7. Replicated divergence in cichlid radiations mirrors a major vertebrate innovation.

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    McGee, Matthew D; Faircloth, Brant C; Borstein, Samuel R; Zheng, Jimmy; Darrin Hulsey, C; Wainwright, Peter C; Alfaro, Michael E

    2016-01-13

    Decoupling of the upper jaw bones--jaw kinesis--is a distinctive feature of the ray-finned fishes, but it is not clear how the innovation is related to the extraordinary diversity of feeding behaviours and feeding ecology in this group. We address this issue in a lineage of ray-finned fishes that is well known for its ecological and functional diversity--African rift lake cichlids. We sequenced ultraconserved elements to generate a phylogenomic tree of the Lake Tanganyika and Lake Malawi cichlid radiations. We filmed a diverse array of over 50 cichlid species capturing live prey and quantified the extent of jaw kinesis in the premaxillary and maxillary bones. Our combination of phylogenomic and kinematic data reveals a strong association between biting modes of feeding and reduced jaw kinesis, suggesting that the contrasting demands of biting and suction feeding have strongly influenced cranial evolution in both cichlid radiations. PMID:26763694

  8. A multi-marker perspective on the evolutionary history of East African cichlid fishes

    OpenAIRE

    Meyer, Britta Silke

    2015-01-01

    The East African cichlids, more precisely the cichlid fishes of Lake Tanganyika, Lake Victoria and Lake Malawi, are among the most famous textbook examples of adaptive radiations. Both hybridization and incomplete lineage sorting explain the high degree of shared gene lineages within these species-flocks. Considerable effort has been put into the understanding of the relationships between and among the main lineages as this is essential to establish the phylogenetic backbone of the East Afric...

  9. The Impact of the Geologic History and Paleoclimate on the Diversification of East African Cichlids

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    Patrick D. Danley

    2012-01-01

    Full Text Available The cichlid fishes of the East African Great Lakes are the largest extant vertebrate radiation identified to date. These lakes and their surrounding waters support over 2,000 species of cichlid fish, many of which are descended from a single common ancestor within the past 10 Ma. The extraordinary East African cichlid diversity is intricately linked to the highly variable geologic and paleoclimatic history of this region. Greater than 10 Ma, the western arm of the East African rift system began to separate, thereby creating a series of rift basins that would come to contain several water bodies, including the extremely deep Lakes Tanganyika and Malawi. Uplifting associated with this rifting backponded many rivers and created the extremely large, but shallow Lake Victoria. Since their creation, the size, shape, and existence of these lakes have changed dramatically which has, in turn, significantly influenced the evolutionary history of the lakes' cichlids. This paper reviews the geologic history and paleoclimate of the East African Great Lakes and the impact of these forces on the region's endemic cichlid flocks.

  10. Back to Tanganyika: a case of recent trans-species-flock dispersal in East African haplochromine cichlid fishes

    OpenAIRE

    Meyer, Britta S.; Indermaur, Adrian; Ehrensperger, Xenia; Egger, Bernd; Banyankimbona, Gaspard; Snoeks, Jos; Salzburger, Walter

    2015-01-01

    The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here,...

  11. Maternal food provisioning in a substrate-brooding African cichlid.

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    Kazutaka Ota

    Full Text Available Fish demonstrate the greatest variety of parental care strategies within the animal kingdom. Fish parents seldom provision food for offspring, with some exceptions predominantly found in substrate-brooding Central American cichlids and mouth-brooding African cichlids. Here, we provide the first evidence of food provisioning in a substrate-brooding African cichlid Neolamprologus mondabu. This fish is a maternal substrate-brooding cichlid endemic to Lake Tanganyika, and feeds on benthic animals using unique techniques-individuals typically feed on the surface of sandy substrates, but also expose prey by digging up substrates with vigorous wriggling of their body and fins. Young also feed on benthos on the substrate surface, but only using the first technique. We observed that feeding induced by digging accounted for 30% of total feeding bouts in adult females, demonstrating that digging is an important foraging tactic. However, parental females fed less frequently after digging than non-parental females, although both females stayed in pits created by digging for approximately 30 s. Instead, young gathered in the pit and fed intensively, suggesting that parental females provision food for young by means of digging. We tested this hypothesis by comparing the feeding frequency of young before and after digging that was simulated by hand, and observed that young doubled their feeding frequency after the simulated digging. This suggests that parental females engage in digging to uncover food items that are otherwise unavailable to young, and provision food for them at the expense of their own foraging. This behavior was similar to what has been observed in Central American cichlids.

  12. Chromosome Evolution in African Cichlid Fish: Contributions from the Physical Mapping of Repeated DNAs

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    Ferreira, I.A.; Poletto, A.B.; Kocher, T.D.; Mota-Velasco, J.C.; Penman, D.J.; Martins, C.

    2010-01-01

    Cichlid fishes have been the subject of increasing scientific interest because of their rapid adaptive radiation that has led to extensive ecological diversity and because of their enormous importance to tropical and subtropical aquaculture. To further understanding of chromosome evolution among cichlid species, we have comparatively mapped the SATA satellite DNA, the transposable element ROn-1, and repeated sequences in the bacterial artificial chromosome clone BAC-C4E09 on the chromosomes of a range of African species of Cichlidae, using fluorescence in situ hybridization. The SATA satellite DNA was mapped in almost all the centromeres of all tilapiine and haplochromine species studied. The maintenance and centromeric distribution of the SATA satellite DNA in African cichlids suggest that this sequence plays an important role in the organization and function of the centromere in these species. Furthermore, analysis of SATA element distribution clarifies that chromosome fusions occurred independently in Oreochromis and Tilapia genera, and led to the reduced chromosome number detected in O. karongae and T. mariae. The comparative chromosome mapping of the ROn-1 SINE-like element and BAC-C4E09 shows that the repeated sequences have been maintained among tilapiine, haplochromine and hemichromine fishes and has demonstrated the homology of the largest chromosomes among these groups. Furthermore, the mapping of ROn-1 suggested that different chromosomal rearrangements could have occurred in the origin of the largest chromosome pairs of tilapiines and non-tilapiines. PMID:20606399

  13. Back to Tanganyika: a case of recent trans-species-flock dispersal in East African haplochromine cichlid fishes

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    Meyer, Britta S.; Indermaur, Adrian; Ehrensperger, Xenia; Egger, Bernd; Banyankimbona, Gaspard; Snoeks, Jos; Salzburger, Walter

    2015-01-01

    The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here, we report the discovery of a haplochromine cichlid species in Lake Tanganyika, which belongs genetically to the species flock of haplochromines of the Lake Victoria region. The new species colonized Lake Tanganyika only recently, suggesting that faunal exchange across watersheds and, hence, between isolated ichthyofaunas, is more common than previously thought. PMID:26064619

  14. The species flocks of East African cichlid fishes: recent advances in molecular phylogenetics and population genetics

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    Salzburger, Walter; Meyer, Axel

    With more than 3,000 species, the fish family Cichlidae is one of the most species-rich families of vertebrates. Cichlids occur in southern and central America, Africa, Madagascar, and India. The hotspot of their biodiversity is East Africa, where they form adaptive radiations composed of hundreds of endemic species in several lakes of various sizes and ages. The unparalleled species richness of East African cichlids has been something of a conundrum for evolutionary biologists and ecologists, since it has been in doubt whether these hundreds of species arose by allopatric speciation or whether it is necessary to invoke somewhat less traditional models of speciation, such as micro-allopatric, peripatric, or even sympatric speciation or evolution through sexual selection mediated by female choice. Ernst Mayr's analyses of these evolutionary uniquely diverse species assemblages have contributed to a more direct approach to this problem and have led to a deeper understanding of the patterns and processes that caused the formation of these huge groups of species. We review here recent molecular data on population differentiation and phylogenetics, which have helped to unravel, to some extent, the patterns and processes that led to the formation and ecological maintenance of cichlid species flocks. It is becoming apparent that sexually selected traits do play an important role in speciation in micro-allopatric or even sympatric settings. Species richness seems to be roughly correlated with the surface area, but not the age, of the lakes. We observe that the oldest lineages of a species flock of cichlids are often less species-rich and live in the open water or deepwater habitats. While the species flocks of the Lake Malawai and the Lake Victoria areas were shown to be monophyletic, the cichlid assemblage of Lake Tanganyika seems to consist of several independent species flocks. Cichlids emerge as an evolutionary model system in which many fundamental questions in

  15. Gut Microbiota Dynamics during Dietary Shift in Eastern African Cichlid Fishes.

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    Laura Baldo

    Full Text Available The gut microbiota structure reflects both a host phylogenetic history and a signature of adaptation to the host ecological, mainly trophic niches. African cichlid fishes, with their array of closely related species that underwent a rapid dietary niche radiation, offer a particularly interesting system to explore the relative contribution of these two factors in nature. Here we surveyed the host intra- and interspecific natural variation of the gut microbiota of five cichlid species from the monophyletic tribe Perissodini of lake Tanganyika, whose members transitioned from being zooplanktivorous to feeding primarily on fish scales. The outgroup riverine species Astatotilapia burtoni, largely omnivorous, was also included in the study. Fusobacteria, Firmicutes and Proteobacteria represented the dominant components in the gut microbiota of all 30 specimens analysed according to two distinct 16S rRNA markers. All members of the Perissodini tribe showed a homogenous pattern of microbial alpha and beta diversities, with no significant qualitative differences, despite changes in diet. The recent diet shift between zooplantkon- and scale-eaters simply reflects on a significant enrichment of Clostridium taxa in scale-eaters where they might be involved in the scale metabolism. Comparison with the omnivorous species A. burtoni suggests that, with increased host phylogenetic distance and/or increasing herbivory, the gut microbiota begins differentiating also at qualitative level. The cichlids show presence of a large conserved core of taxa and a small set of core OTUs (average 13-15%, remarkably stable also in captivity, and putatively favoured by both restricted microbial transmission among related hosts (putatively enhanced by mouthbrooding behavior and common host constraints. This study sets the basis for a future large-scale investigation of the gut microbiota of cichlids and its adaptation in the process of the host adaptive radiation.

  16. What, if anything, is a Tilapia?-mitochondrial ND2 phylogeny of tilapiines and the evolution of parental care systems in the African cichlid fishes.

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    Klett, Vera; Meyer, Axel

    2002-06-01

    We estimated a novel phylogeny of tilapiine cichlid fish (an assemblage endemic to Africa and the Near East) within the African cichlid fishes on the basis of complete mitochondrial NADH dehydrogenase subunit 2 (ND2) gene sequences. The ND2 (1,047 bp) gene was sequenced in 39 tilapiine cichlids (38 species and 1 subspecies) and in an additional 14 nontilapiine cichlid species in order to evaluate the traditional morphologically based hypothesis of the respective monophyly of the tilapiine and haplochromine cichlid fish assemblages. The analyses included many additional cichlid lineages, not only the so-called tilapiines, but also lineages from Lake Tanganyika, east Africa, the Neotropics and an out-group from Madagascar with a wide range of parental care and mating systems. Our results suggest, in contrast to the historical morphology-based hypotheses from Regan (1920, 1922 ), Trewavas (1983), and Stiassny (1991), that the tilapiines do not form a monophyletic group because there is strong evidence that the genus Tilapia is not monophyletic but divided into at least five distinct groups. In contrast to this finding, an allozyme analysis of Pouyaud and Agnèse (1995), largely based on the same samples as used here, found a clustering of the Tilapia species into only two groups. This discrepancy is likely caused by the difference in resolution power of the two marker systems used. Our data suggest that only type species Tilapia sparrmanii Smith (1840) should retain the genus name TILAPIA: One particular group of tilapiines (composed of genera Sarotherodon, Oreochromis, Iranocichla, and Tristramella) is more closely related to an evolutionarily highly successful lineage, the haplochromine cichlids that compose the adaptive radiations of cichlid species flocks of east Africa. It appears that the highly adaptable biology of tilapiines is the ancestral state for all African cichlids and that the more stenotypic lifestyle of the haplochromine cichlids is derived from this

  17. Complex patterns of divergence among green-sensitive (RH2a African cichlid opsins revealed by Clade model analyses

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    Weadick Cameron J

    2012-10-01

    Full Text Available Abstract Background Gene duplications play an important role in the evolution of functional protein diversity. Some models of duplicate gene evolution predict complex forms of paralog divergence; orthologous proteins may diverge as well, further complicating patterns of divergence among and within gene families. Consequently, studying the link between protein sequence evolution and duplication requires the use of flexible substitution models that can accommodate multiple shifts in selection across a phylogeny. Here, we employed a variety of codon substitution models, primarily Clade models, to explore how selective constraint evolved following the duplication of a green-sensitive (RH2a visual pigment protein (opsin in African cichlids. Past studies have linked opsin divergence to ecological and sexual divergence within the African cichlid adaptive radiation. Furthermore, biochemical and regulatory differences between the RH2aα and RH2aβ paralogs have been documented. It thus seems likely that selection varies in complex ways throughout this gene family. Results Clade model analysis of African cichlid RH2a opsins revealed a large increase in the nonsynonymous-to-synonymous substitution rate ratio (ω following the duplication, as well as an even larger increase, one consistent with positive selection, for Lake Tanganyikan cichlid RH2aβ opsins. Analysis using the popular Branch-site models, by contrast, revealed no such alteration of constraint. Several amino acid sites known to influence spectral and non-spectral aspects of opsin biochemistry were found to be evolving divergently, suggesting that orthologous RH2a opsins may vary in terms of spectral sensitivity and response kinetics. Divergence appears to be occurring despite intronic gene conversion among the tandemly-arranged duplicates. Conclusions Our findings indicate that variation in selective constraint is associated with both gene duplication and divergence among orthologs in African

  18. A robust phylogeny among major lineages of the East African cichlids.

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    Takahashi, Tetsumi; Sota, Teiji

    2016-07-01

    The huge monophyletic group of the East African cichlid radiations (EAR) consists of thousands of species belonging to 12-14 tribes; the number of tribes differs among studies. Many studies have inferred phylogenies of EAR tribes using various genetic markers. However, these phylogenies partly contradict one another and can have weak statistic support. In this study, we conducted maximum-likelihood (ML) phylogenetic analyses using restriction site-associated DNA (RAD) sequences and propose a new robust phylogenetic hypothesis among Lake Tanganyika cichlid fishes, which cover most EAR tribes. Data matrices can vary in size and contents depending on the strategies used to process RAD sequences. Therefore, we prepared 23 data matrices with various processing strategies. The ML phylogenies inferred from 15 large matrices (2.0×10(6) to 1.1×10(7) base pairs) resolved every tribe as a monophyletic group with 100% bootstrap support and shared the same topology regarding relationships among the tribes. Most nodes among the tribes were supported by 100% bootstrap values, and the bootstrap support for the other node varied among the 15 ML trees from 70% to 100%. These robust ML trees differ partly in topology from those in earlier studies, and these phylogenetic relationships have important implications for the tribal classification of EAR. PMID:27068840

  19. Phylogeny of the Lake Tanganyika cichlid species flock and its relationship to the Central and East African haplochromine cichlid fish fauna

    OpenAIRE

    Salzburger, Walter; Meyer, Axel; Baric, Sanja; Verheyen, Erik; Sturmbauer, Christian

    2002-01-01

    Lake Tanganyika, the oldest of the East African Great Lakes, harbors the ecologically, morphologically, and behaviorally most complex of all assemblages of cichlid Fishes, consisting of about 200 described species. The evolutionary old age of the cichlid assemblage, its extreme degree of morphological differentiation, the lack of species with intermediate morphologies, and the rapidity of lineage formation havemade evolutionary reconstruction difficult. The number and origin of seeding lineag...

  20. Social fishes and single mothers: brain evolution in African cichlids

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    Gonzalez-Voyer, Alejandro; Winberg, Svante; Kolm, Niclas

    2008-01-01

    As with any organ, differences in brain size—after adequate control of allometry—are assumed to be a response to selection. With over 200 species and an astonishing diversity in niche preferences and social organization, Tanganyikan cichlids present an excellent opportunity to study brain evolution. We used phylogenetic comparative analyses of sexed adults from 39 Tanganyikan cichlid species in a multiple regression framework to investigate the influence of ecology, sexual selection and paren...

  1. What, if anything, is a Tilapia? : Mitochondrial ND2 phylogeny of Tilapiines and the evolution of parental care systems in the African Cichlid Fishes

    OpenAIRE

    Klett, Vera; Meyer, Axel

    2002-01-01

    We estimated a novel phylogeny of tilapiine cichlid fish (an assemblage endemic to Africa and the Near East) within the African cichlid fishes on the basis of complete mitochondrial NADH dehydrogenase subunit 2 (ND2) gene sequences. The ND2 (1,047 bp) gene was sequenced in 39 tilapiine cichlids (38 species and 1 subspecies) and in an additional 14 nontilapiine cichlid species in order to evaluate the traditional morphologically based hypothesis of the respective monophyly of the tilapiine and...

  2. The Adaptive Radiation of Cichlid Fish in Lake Tanganyika: A Morphological Perspective

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    Tetsumi Takahashi

    2011-01-01

    Full Text Available Lake Tanganyika is the oldest of the Great Ancient Lakes in the East Africa. This lake harbours about 250 species of cichlid fish, which are highly diverse in terms of morphology, behaviour, and ecology. Lake Tanganyika's cichlid diversity has evolved through explosive speciation and is treated as a textbook example of adaptive radiation, the rapid differentiation of a single ancestor into an array of species that differ in traits used to exploit their environments and resources. To elucidate the processes and mechanisms underlying the rapid speciation and adaptive radiation of Lake Tanganyika's cichlid species assemblage it is important to integrate evidence from several lines of research. Great efforts have been, are, and certainly will be taken to solve the mystery of how so many cichlid species evolved in so little time. In the present review, we summarize morphological studies that relate to the adaptive radiation of Lake Tanganyika's cichlids and highlight their importance for understanding the process of adaptive radiation.

  3. Modularity of the Oral Jaws Is Linked to Repeated Changes in the Craniofacial Shape of African Cichlids

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    Kevin J. Parsons

    2011-01-01

    Full Text Available The African cichlids of the East-African rift-lakes provide one of the most dramatic examples of adaptive radiation known. It has long been thought that functional decoupling of the oral and pharyngeal jaws in cichlids has facilitated their explosive evolution. Recent research has also shown that craniofacial evolution from radiations in lakes Victoria, Malawi, and Tanganyika has occurred along a shared primary axis of shape divergence, whereby the preorbital region of the skull changes in a manner that is, relatively independent from other head regions. We predicted that the preorbital region would comprise a variational module and used an extensive dataset from each lake that allowed us to test this prediction using a model selection approach. Our findings supported the presence of a preorbital module across all lakes, within each lake, and for Malawi, within sand and rock-dwelling clades. However, while a preorbital module was consistently present, notable differences were also observed among groups. Of particular interest, a negative association between patterns of variational modularity was observed between the sand and rock-dwelling clades, a patter consistent with character displacement. These findings provide the basis for further experimental research involving the determination of the developmental and genetic bases of these patterns of modularity.

  4. Genetic divergence, speciation and morphological stasis in a lineage of African cichlid fishes

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    Sturmbauer, Christian; Meyer, Axel

    1992-01-01

    Since their discovery at the turn of the century, the species assemblages of cichlid fishes in the East African Lakes Victoria, Malawi and Tanganyika have fascinated evolutionary biologists. Many models have attempted to account for the 'explosive' evolution of several hundred species within these lakes. Here we report a case of surprisingly large genetic divergence among populations of the endemic Tropheus lineage of Lake Tanganyika. This lineage of six species contains twice as much genetic...

  5. Fish & Chips: Functional Genomics of Social Plasticity in an African Cichlid Fish

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    Renn, Susan C.P.; Aubin-Horth, Nadia; Hofmann, Hans A.

    2008-01-01

    Behaviour and physiology are regulated by both environment and social context. A central goal in the study of the social control of behaviour is to determine the underlying physiological, cellular and molecular mechanisms in the brain. The African cichlid fish Astatotilapia burtoni has long been used as a model system to study how social interactions regulate neural and behavioural plasticity. In this species, males are either socially dominant and reproductively active or subordinate and rep...

  6. Social context may affect urinary excretion of 11-ketotestosterone in african cichlids

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    Hirschenhauser, Katharina; Canário, Adelino V. M.; Ros, Albert F. H.; Taborsky, Michael; Oliveira, Rui Filipe

    2008-01-01

    We previously investigated the androgen responsiveness of males to simulated partner and territory intrusions in five African cichlid species (Neolamprologus pulcher, Lamprologus callipterus, Tropheus moorii, Pseudosimochromis curvifrons, Oreochromis mossambicus; Hirschenhauser et al., 2004). Here we re-analysed data on 11-ketotestosterone (11-KT) levels in holding water to compare the free (presumably from the gills) and conjugated (presumably from urine and faeces) 11-KT frac...

  7. The evolution of complex brains and behaviors in African cichlid fishes

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    Caroly A. Shumway

    2010-02-01

    Full Text Available In this review, I explore the effects of both social organization and the physical environment, specifically habitat complexity, on the brains and behavior of highly visual African cichlid fishes, drawing on examples from primates and birds where appropriate. In closely related fishes from the monophyletic Ectodinii clade of Lake Tanganyika, both forces influence cichlid brains and behavior. Considering social influences first, visual acuity differs with respect to social organization (monogamy versus polygyny. Both the telencephalon and amygdalar homologue, area Dm, are larger in monogamous species. Monogamous species are found to have more vasotocin-immunoreactive cells in the preoptic area of the brain. Habitat complexity also influences brain and behavior in these fishes. Total brain size, telencephalic and cerebellar size are positively correlated with habitat complexity. Visual acuity and spatial memory are enhanced in cichlids living in more complex environments. However habitat complexity and social forces affect cichlid brains differently. Taken together, our field data and plasticity data suggest that some of the species-specific neural effects of habitat complexity could be the consequence of the corresponding social correlates. Environmental forces, however, exert a broader effect on brain structures than social ones do, suggesting allometric expansion of the brain structures in concert with brain size and/or co-evolution of these structures [Current Zoology 56 (1: 144–156 2010].

  8. The Adaptive Radiation of Cichlid Fish in Lake Tanganyika: A Morphological Perspective

    OpenAIRE

    Tetsumi Takahashi; Stephan Koblmüller

    2011-01-01

    Lake Tanganyika is the oldest of the Great Ancient Lakes in the East Africa. This lake harbours about 250 species of cichlid fish, which are highly diverse in terms of morphology, behaviour, and ecology. Lake Tanganyika's cichlid diversity has evolved through explosive speciation and is treated as a textbook example of adaptive radiation, the rapid differentiation of a single ancestor into an array of species that differ in traits used to exploit their environments and resources. To elucidate...

  9. Process and pattern in cichlid radiations - inferences for understanding unusually high rates of evolutionary diversification.

    Science.gov (United States)

    Seehausen, Ole

    2015-07-01

    The cichlid fish radiations in the African Great Lakes differ from all other known cases of rapid speciation in vertebrates by their spectacular trophic diversity and richness of sympatric species, comparable to the most rapid angiosperm radiations. I review factors that may have facilitated these radiations and compare these with insights from recent work on plant radiations. Work to date suggests that it was a coincidence of ecological opportunity, intrinsic ecological versatility and genomic flexibility, rapidly evolving behavioral mate choice and large amounts of standing genetic variation that permitted these spectacular fish radiations. I propose that spatially orthogonal gradients in the fit of phenotypes to the environment facilitate speciation because they allow colonization of alternative fitness peaks during clinal speciation despite local disruptive selection. Such gradients are manifold in lakes because of the interaction of water depth as an omnipresent third spatial dimension with other fitness-relevant variables. I introduce a conceptual model of adaptive radiation that integrates these elements and discuss its applicability to, and predictions for, plant radiations. PMID:25983053

  10. Lake Tanganyika—A 'Melting Pot' of Ancient and Young Cichlid Lineages (Teleostei: Cichlidae)?

    OpenAIRE

    Weiss, Juliane D.; Cotterill, Fenton P. D.; Schliewen, Ulrich K

    2015-01-01

    A long history of research focused on the East Africa cichlid radiations (EAR) revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tan...

  11. Big fish, little divergence: phylogeography of Lake Tanganyika’s giant cichlid, Boulengerochromis microlepis

    OpenAIRE

    Koblmüller, Stephan; Elizabeth A. Odhiambo; Sinyinza, Danny; Sturmbauer, Christian; Sefc, Kristina M

    2015-01-01

    The largely endemic cichlid species flocks of the East African Great Lakes are among the prime examples for explosive speciation and adaptive radiation. Speciation rates differ among cichlid lineages, and the propensity to radiate has been linked to intrinsic and extrinsic factors such as sexual selection and ecological opportunity. Remarkably, only one cichlid tribe—the Boulengerochromini—comprises just a single species, Boulengerochromis microlepis, a predominantly piscivorous endemic of La...

  12. The interaction of sexually and naturally selected traits in the adaptive radiations of cichlid fishes.

    Science.gov (United States)

    Salzburger, Walter

    2009-01-01

    The question of how genetic variation translates into organismal diversity has puzzled biologists for decades. Despite recent advances in evolutionary and developmental genetics, the mechanisms that underlie adaptation, diversification and evolutionary innovation remain largely unknown. The exceptionally diverse species flocks of cichlid fishes are textbook examples of adaptive radiation and explosive speciation and emerge as powerful model systems to study the genetic basis of animal diversification. East Africa's hundreds of endemic cichlid species are akin to a natural mutagenesis screen and differ greatly not only in ecologically relevant (hence naturally selected) characters such as mouth morphology and body shape, but also in sexually selected traits such as coloration. One of the most fascinating aspects of cichlid evolution is the frequent occurrence of evolutionary parallelisms, which has led to the question whether selection alone is sufficient to produce these parallel morphologies, or whether a developmental or genetic bias has influenced the direction of diversification. Here, I review fitness-relevant traits that could be responsible for the cichlids' evolutionary success and assess whether these were shaped by sexual or natural selection. I then focus on the interaction and the relative importance of sexual vs. natural selection in cichlid evolution. Finally, I discuss what is currently known about the genes underlying the morphogenesis of adaptively relevant traits and highlight the importance of the forthcoming cichlid genomes in the quest of the genetic basis of diversification in this group. PMID:18992003

  13. Origin of the superflock of cichlid fishes from Lake Victoria, East Africa

    OpenAIRE

    Verheyen, Erik; Salzburger, Walter; Snoeks, Jos; Meyer, Axel

    2003-01-01

    Lake Victoria harbors a unique species-rich flock of more than 500 endemic haplochromine cichlid fishes. The origin, age, and mechanism of diversification of this extraordinary radiation are still debated. Geological evidence suggests that the lake dried out completely about 14,700 years ago.Onthe basis of phylogenetic analyses of almost 300 DNA sequences of the mitochondrial control region of East African cichlids, we find that the Lake Victoria cichlid flock is derived from the geologically...

  14. Continental cichlid radiations: functional diversity reveals the role of changing ecological opportunity in the Neotropics.

    Science.gov (United States)

    Arbour, Jessica Hilary; López-Fernández, Hernán

    2016-08-17

    Adaptive radiations have been hypothesized to contribute broadly to the diversity of organisms. Models of adaptive radiation predict that ecological opportunity and ecological release, the availability of empty ecological niches and the response by adapting lineages to occupy them, respectively, drive patterns of phenotypic and lineage diversification. Adaptive radiations driven by 'ecological opportunity' are well established in island systems; it is less clear if ecological opportunity influences continent-wide diversification. We use Neotropical cichlid fishes to test if variation in rates of functional evolution is consistent with changing ecological opportunity. Across a functional morphological axis associated with ram-suction feeding traits, evolutionary rates declined through time as lineages diversified in South America. Evolutionary rates of ram-suction functional morphology also appear to have accelerated as cichlids colonized Central America and encountered renewed opportunity. Our results suggest that ecological opportunity may play an important role in shaping patterns of morphological diversity of even broadly distributed lineages like Neotropical cichlids. PMID:27512144

  15. Adaptive phenotypic plasticity in the Midas cichlid fish pharyngeal jaw and its relevance in adaptive radiation

    Directory of Open Access Journals (Sweden)

    Salzburger Walter

    2011-04-01

    Full Text Available Abstract Background Phenotypic evolution and its role in the diversification of organisms is a central topic in evolutionary biology. A neglected factor during the modern evolutionary synthesis, adaptive phenotypic plasticity, more recently attracted the attention of many evolutionary biologists and is now recognized as an important ingredient in both population persistence and diversification. The traits and directions in which an ancestral source population displays phenotypic plasticity might partly determine the trajectories in morphospace, which are accessible for an adaptive radiation, starting from the colonization of a novel environment. In the case of repeated colonizations of similar environments from the same source population this "flexible stem" hypothesis predicts similar phenotypes to arise in repeated subsequent radiations. The Midas Cichlid (Amphilophus spp. in Nicaragua has radiated in parallel in several crater-lakes seeded by populations originating from the Nicaraguan Great Lakes. Here, we tested phenotypic plasticity in the pharyngeal jaw of Midas Cichlids. The pharyngeal jaw apparatus of cichlids, a second set of jaws functionally decoupled from the oral ones, is known to mediate ecological specialization and often differs strongly between sister-species. Results We performed a common garden experiment raising three groups of Midas cichlids on food differing in hardness and calcium content. Analyzing the lower pharyngeal jaw-bones we find significant differences between diet groups qualitatively resembling the differences found between specialized species. Observed differences in pharyngeal jaw expression between groups were attributable to the diet's mechanical resistance, whereas surplus calcium in the diet was not found to be of importance. Conclusions The pharyngeal jaw apparatus of Midas Cichlids can be expressed plastically if stimulated mechanically during feeding. Since this trait is commonly differentiated - among

  16. Genomic islands of speciation separate cichlid ecomorphs in an East African crater lake.

    Science.gov (United States)

    Malinsky, Milan; Challis, Richard J; Tyers, Alexandra M; Schiffels, Stephan; Terai, Yohey; Ngatunga, Benjamin P; Miska, Eric A; Durbin, Richard; Genner, Martin J; Turner, George F

    2015-12-18

    The genomic causes and effects of divergent ecological selection during speciation are still poorly understood. Here we report the discovery and detailed characterization of early-stage adaptive divergence of two cichlid fish ecomorphs in a small (700 meters in diameter) isolated crater lake in Tanzania. The ecomorphs differ in depth preference, male breeding color, body shape, diet, and trophic morphology. With whole-genome sequences of 146 fish, we identified 98 clearly demarcated genomic "islands" of high differentiation and demonstrated the association of genotypes across these islands with divergent mate preferences. The islands contain candidate adaptive genes enriched for functions in sensory perception (including rhodopsin and other twilight-vision-associated genes), hormone signaling, and morphogenesis. Our study suggests mechanisms and genomic regions that may play a role in the closely related mega-radiation of Lake Malawi. PMID:26680190

  17. As clear as mud: Turbidity induces behavioral changes in the African cichlid Pseudocrenilabrus multicolor

    Institute of Scientific and Technical Information of China (English)

    Suzanne M. GRAY; Laura H. McDONNELL; Fabio G. CINQUEMANI; Lauren J. CHAPMAN

    2012-01-01

    Aquatic biodiversity is being lost at an unprecedented rate.One factor driving this loss is increased turbidity,an environmental stressor that can impose behavioral,morphological,and/or physiological costs on fishes.Here we describe the behavioral response of a widespread African cichlid,Pseudocrenilabrus multicolor victoriae,to turbidity.We used a split-brood rearing design to test if F1 offspring reared in turbid water,originating from river (turbid) and swamp (clear) populations,behave differently than full-sibs reared in clear water.We examined two facets of behavior:(1) behaviors of fish in full sib groups,including activity level and social dynamics collected during the rearing period; and (2) male aggressive behavior directed at potential male competitors after fish had reached maturity; this was done in an experimental set-up independent of the rearing aquaria.Regardless of population of origin,fish reared in turbid water were marginally less active and performed fewer social behaviors than those reared in clear water.On the other hand,when tested against a competitor in turbid water,males performed more aggressive behaviors,regardless of population of origin or rearing environment.Our results suggest a plastic behavioral response to turbidity that may allow P multicolor to persist over a range of turbidity levels in nature by decreasing activity and general social behaviors and intensifying reproductive behaviors to ensure reproductive success [ Current Zoology 58 (1):146-157,2012].

  18. Chromosome differentiation patterns during cichlid fish evolution

    Directory of Open Access Journals (Sweden)

    Nirchio Mauro

    2010-06-01

    Full Text Available Abstract Background Cichlid fishes have been the subject of increasing scientific interest because of their rapid adaptive radiation which has led to an extensive ecological diversity and their enormous importance to tropical and subtropical aquaculture. To increase our understanding of chromosome evolution among cichlid species, karyotypes of one Asian, 22 African, and 30 South American cichlid species were investigated, and chromosomal data of the family was reviewed. Results Although there is extensive variation in the karyotypes of cichlid fishes (from 2n = 32 to 2n = 60 chromosomes, the modal chromosome number for South American species was 2n = 48 and the modal number for the African ones was 2n = 44. The only Asian species analyzed, Etroplus maculatus, was observed to have 46 chromosomes. The presence of one or two macro B chromosomes was detected in two African species. The cytogenetic mapping of 18S ribosomal RNA (18S rRNA gene revealed a variable number of clusters among species varying from two to six. Conclusions The karyotype diversification of cichlids seems to have occurred through several chromosomal rearrangements involving fissions, fusions and inversions. It was possible to identify karyotype markers for the subfamilies Pseudocrenilabrinae (African and Cichlinae (American. The karyotype analyses did not clarify the phylogenetic relationship among the Cichlinae tribes. On the other hand, the two major groups of Pseudocrenilabrinae (tilapiine and haplochromine were clearly discriminated based on the characteristics of their karyotypes. The cytogenetic mapping of 18S ribosomal RNA (18S rRNA gene did not follow the chromosome diversification in the family. The dynamic evolution of the repeated units of rRNA genes generates patterns of chromosomal distribution that do not help follows the phylogenetic relationships among taxa. The presence of B chromosomes in cichlids is of particular interest because they may not be represented in

  19. Molecular phylogeny and evidence for an adaptive radiation of geophagine cichlids from South America (Perciformes: Labroidei).

    Science.gov (United States)

    López-Fernández, Hernán; Honeycutt, Rodney L; Winemiller, Kirk O

    2005-01-01

    Nucleotide sequences from the mitochondrial ND4 gene and the nuclear RAG2 gene were used to derive the most extensive molecular phylogeny to date for the Neotropical cichlid subfamily Geophaginae. Previous hypotheses of relationships were tested in light of these new data and a synthesis of all existing molecular information was provided. Novel phylogenetic findings included support for : (1) a 'Big Clade' containing the genera Geophagus sensu lato, Gymnogeophagus, Mikrogeophagus, Biotodoma, Crenicara, and Dicrossus; (2) a clade including the genera Satanoperca, Apistogramma, Apistogrammoides, and Taeniacara; and (3) corroboration for Kullander's clade Acarichthyini. ND4 demonstrated saturation effects at the third code position and lineage-specific rate heterogeneity, both of which influenced phylogeny reconstruction when only equal weighted parsimony was employed. Both branch lengths and internal branch tests revealed extremely short basal nodes that add support to the idea that geophagine cichlids have experienced an adaptive radiation sensu Schluter that involved ecomorphological specializations and life history diversification. PMID:15579395

  20. Contrasting parasite communities among allopatric colour morphs of the Lake Tanganyika cichlid Tropheus

    OpenAIRE

    Raeymaekers, Joost; Hablützel, Pascal István; Grégoir, Arnout; Bamps, Jolien; Roose, Anna; Vanhove, Maarten; Van SteenBerge, Maarten; Pariselle, Antoine; Huyse, Tine; Snoeks, Jos; VOLCKAERT Filip

    2013-01-01

    Background: Adaptation to different ecological environments is thought to drive ecological speciation. This phenomenon culminates in the radiations of cichlid fishes in the African Great Lakes. Multiple characteristic traits of cichlids, targeted by natural or sexual selection, are considered among the driving factors of these radiations. Parasites and pathogens have been suggested to initiate or accelerate speciation by triggering both natural and sexual selection. Three prerequisites for pa...

  1. Repeated trans-watershed hybridization among haplochromine cichlids (Cichlidae) was triggered by Neogene landscape evolution

    OpenAIRE

    Schwarzer, Julia; Swartz, Ernst Roelof; Vreven, Emmanuel; Snoeks, Jos; Cotterill, Fenton Peter David; Misof, Bernhard; Schliewen, Ulrich Kurt

    2012-01-01

    The megadiverse haplochromine cichlid radiations of the East African lakes, famous examples of explosive speciation and adaptive radiation, are according to recent studies, introgressed by different riverine lineages. This study is based on the first comprehensive mitochondrial and nuclear DNA dataset from extensive sampling of riverine haplochromine cichlids. It includes species from the lower River Congo and Angolan (River Kwanza) drainages. Reconstruction of phylogenetic hypotheses reveale...

  2. Fish embryo and juvenile size under hypoxia in the mouth-brooding African cichlid Pseudocrenilabrus multicolor

    Institute of Scientific and Technical Information of China (English)

    E.E.REARDON; L.J.CHAPMAN

    2012-01-01

    We used a field survey and a laboratory rearing experiment to (a) examine response (size and survival) to life-long hypoxia in offspring of the African maternal mouth-brooding cichlid Pseudocrenilabrus multicolor victoriae (Seegers) and (b) explore the degree to which developmental response can be environmentally-induced.Embryo size metrics were quantified in 9 field populations across a range of dissolved oxygen (DO) concentrations.In the laboratory,first generation (F1) broods of low-DO origin were reared under high or low DO.Brooding period was quantified for the mothers; and egg size,egg metabolic rate and juvenile size-at-release were quantified in their (F2) offspring.The F2 offspring were split and grown for 3 months post-release under high or low DO,and juvenile size and survival were quantified.In the field survey,across stages,embryos from low-DO field populations were shorter and weighed less than embryos from high-DO populations.In the laboratory experiment,F2 eggs and juveniles-at-release from mother's mouth did not differ in mass,length,survival regardless of development DO environment.However,juveniles diverged in size after leaving mother's mouth,exhibiting smaller size when grown under low DO.Size differences in embryo size across field populations and divergence in embryo size after release from the mother's mouthsupport predictions for smaller body size under hypoxia.There was no evidence for negative effects on survival of juveniles after 3 months.Brooding period was 16% shorter in females reared under low DO suggesting that hypoxia may accelerate embryo development.This work provides insights into how bearer fishes respond to hypoxic stress relative to fishes with no post-spawning parental care; a shorter brooding interval and smaller body size may provide an optimal solution to parent and embryo survival under hypoxia in brooding fishes.

  3. The role of physiology in the divergence of two incipient cichlid species

    OpenAIRE

    Dijkstra, P. D.; Wiegertjes, G.F.; Forlenza, M.; van der Sluijs, I.; Hofmann, H. A.; Metcalfe, N. B.; Groothuis, T. G. G.

    2011-01-01

    Sexual selection on male coloration has been implicated in the evolution of colourful species flocks of East African cichlid fish. During adaptive radiations, animals diverge in multiple phenotypic traits, but the role of physiology has received limited attention. Here, we report how divergence in physiology may contribute to the stable coexistence of two hybridizing incipient species of cichlid fish from Lake Victoria. Males of Pundamilia nyererei (males are red) tend to defeat those of Pund...

  4. Cutting the Gordian knot:Complex signaling in African cichlids is more than multimodal

    Institute of Scientific and Technical Information of China (English)

    Moira J.VAN STAADEN; Adam R.SMITH

    2011-01-01

    The active transmission of information from sender to recelver is a fundamental component of communication,and is therefore a primary facet in evolutionary models of sexual selection.Research in several systetms has underlined the importance of multiple sensory modalities in courtship signals.However,we still tend to think of individuals as having a relatively static signal in consecutive communicative events.While this may be true for certain traits such as body size or coloration,behaviorally modulated signals can quickly violate this assumption.In this work,we explore how intraspecific variation may be an important component of interspeclfic signal divergence using cichlid fishes from Lake Maiawi.Behavloral analyses were made using six species of Malawian cichlids from two divergent genera.while interspecific differences were found between congeners based on species-level analyses of both acoustic and audiovisual signais,intraspecific variation was of a similar magnitude.Specifically,individual fishes were found to possess highiy plastic signal repertoires.This finding was ubiquitous across all species and resulted in a great deal of overlap between heterospecific individuals,despite statistically distinct species means.These results demonstrate that some aspects of courtship in Malawian cichlids are more plastic than previously proposed,and that studies must account for signal variability within individuals.We propose here that bebavioral variability in signaling is important in determining the communication landscape on which signals are perceived.We review potential complexity deriving from multimodal signaling,discuss the sources for such lability,and suggest ways in which is issue may be approached experimentally.

  5. Nuclear markers reveal unexpected genetic variation and a Congolese-Nilotic origin of the Lake Victoria cichlid species flock.

    OpenAIRE

    Seehausen, Ole; Koetsier, Egbert; Schneider, Maria Victoria; Chapman, Lauren J.; Colin A Chapman; Knight, Mairi E.; Turner, George F.; van Alphen, Jacques J.M; Bills, Roger

    2003-01-01

    Phylogenetic analyses based on mitochondrial (mt) DNA have indicated that the cichlid species flock of the Lake Victoria region is derived from a single ancestral species found in East African rivers, closely related to the ancestor of the Lake Malawi cichlid species flock. The Lake Victoria flock contains ten times less mtDNA variation than the Lake Malawi radiation, consistent with current estimates of the ages of the lakes. We present results of a phylogenetic investigation using nuclear (...

  6. Origin of the superflock of cichlid fishes from Lake Victoria, East Africa.

    Science.gov (United States)

    Verheyen, Erik; Salzburger, Walter; Snoeks, Jos; Meyer, Axel

    2003-04-11

    Lake Victoria harbors a unique species-rich flock of more than 500 endemic haplochromine cichlid fishes. The origin, age, and mechanism of diversification of this extraordinary radiation are still debated. Geological evidence suggests that the lake dried out completely about 14,700 years ago. On the basis of phylogenetic analyses of almost 300 DNA sequences of the mitochondrial control region of East African cichlids, we find that the Lake Victoria cichlid flock is derived from the geologically older Lake Kivu. We suggest that the two seeding lineages may have already been lake-adapted when they colonized Lake Victoria. A haplotype analysis further shows that the most recent desiccation of Lake Victoria did not lead to a complete extinction of its endemic cichlid fauna and that the major lineage diversification took place about 100,000 years ago. PMID:12649486

  7. The B chromosomes of the African cichlid fish Haplochromis obliquidens harbour 18S rRNA gene copies

    Directory of Open Access Journals (Sweden)

    Martins Cesar

    2010-01-01

    Full Text Available Abstract Background Diverse plant and animal species have B chromosomes, also known as accessory, extra or supernumerary chromosomes. Despite being widely distributed among different taxa, the genomic nature and genetic behavior of B chromosomes are still poorly understood. Results In this study we describe the occurrence of B chromosomes in the African cichlid fish Haplochromis obliquidens. One or two large B chromosome(s occurring in 39.6% of the analyzed individuals (both male and female were identified. To better characterize the karyotype and assess the nature of the B chromosomes, fluorescence in situ hybridization (FISH was performed using probes for telomeric DNA repeats, 18S and 5S rRNA genes, SATA centromeric satellites, and bacterial artificial chromosomes (BACs enriched in repeated DNA sequences. The B chromosomes are enriched in repeated DNAs, especially non-active 18S rRNA gene-like sequences. Conclusion Our results suggest that the B chromosome could have originated from rDNA bearing subtelo/acrocentric A chromosomes through formation of an isochromosome, or by accumulation of repeated DNAs and rRNA gene-like sequences in a small proto-B chromosome derived from the A complement.

  8. Ancyrocephalidae (Monogenea) of Lake Tanganyika. III : Cichlidogyrus infecting the world's biggest cichlid and the non-endemic tribes Haplochromini, Oreochromini and Tylochromini (Teleostei, Cichlidae)

    OpenAIRE

    Bukinga, F. M.; Vanhove, M.P.M.; Van Steenberge, M.; Pariselle, Antoine

    2012-01-01

    Lake Tanganyika is the deepest and oldest African Great Lake and of economic importance. While the diversity of its endemic cichlid radiations yielded scientific interest, a number of cichlid tribes have few representatives in the lake. Some of those, namely Oreochromini (ex-Tilapiini), Haplochromini and Tylochromini, reach higher species numbers in riverine systems. Conversely, the phylogenetic position of the monospecific and endemic Boulengerochromini is unclear. The oreochromines Oreochro...

  9. A tribal level phylogeny of Lake Tanganyika cichlid fishes based on a genomic multi-marker approach.

    Science.gov (United States)

    Meyer, Britta S; Matschiner, Michael; Salzburger, Walter

    2015-02-01

    The species-flocks of cichlid fishes in the East African Great Lakes Victoria, Malawi and Tanganyika constitute the most diverse extant adaptive radiations in vertebrates. Lake Tanganyika, the oldest of the lakes, harbors the morphologically and genetically most diverse assemblage of cichlids and contains the highest number of endemic cichlid genera of all African lakes. Based on morphological grounds, the Tanganyikan cichlid species have been grouped into 12-16 distinct lineages, so-called tribes. While the monophyly of most of the tribes is well established, the phylogenetic relationships among the tribes remain largely elusive. Here, we present a new tribal level phylogenetic hypothesis for the cichlid fishes of Lake Tanganyika that is based on the so far largest set of nuclear markers and a total alignment length of close to 18kb. Using next-generation amplicon sequencing with the 454 pyrosequencing technology, we compiled a dataset consisting of 42 nuclear loci in 45 East African cichlid species, which we subjected to maximum likelihood and Bayesian inference phylogenetic analyses. We analyzed the entire concatenated dataset and each marker individually, and performed a Bayesian concordance analysis and gene tree discordance tests. Overall, we find strong support for a position of the Oreochromini, Boulengerochromini, Bathybatini and Trematocarini outside of a clade combining the substrate spawning Lamprologini and the mouthbrooding tribes of the 'H-lineage', which are both strongly supported to be monophyletic. The Eretmodini are firmly placed within the 'H-lineage', as sister-group to the most species-rich tribe of cichlids, the Haplochromini. The phylogenetic relationships at the base of the 'H-lineage' received less support, which is likely due to high speciation rates in the early phase of the radiation. Discordance among gene trees and marker sets further suggests the occurrence of past hybridization and/or incomplete lineage sorting in the cichlid

  10. Variable light environments induce plastic spectral tuning by regional opsin coexpression in the African cichlid fish, Metriaclima zebra.

    Science.gov (United States)

    Dalton, Brian E; Lu, Jessica; Leips, Jeff; Cronin, Thomas W; Carleton, Karen L

    2015-08-01

    Critical behaviours such as predation and mate choice often depend on vision. Visual systems are sensitive to the spectrum of light in their environment, which can vary extensively both within and among habitats. Evolutionary changes in spectral sensitivity contribute to divergence and speciation. Spectral sensitivity of the retina is primarily determined by visual pigments, which are opsin proteins bound to a chromophore. We recently discovered that photoreceptors in different regions of the retina, which view objects against distinct environmental backgrounds, coexpress different pairs of opsins in an African cichlid fish, Metriaclima zebra. This coexpression tunes the sensitivity of the retinal regions to the corresponding backgrounds and may aid in detection of dark objects, such as predators. Although intraretinal regionalization of spectral sensitivity in many animals correlates with their light environments, it is unknown whether variation in the light environment induces developmentally plastic alterations of intraretinal sensitivity regions. Here, we demonstrate with fluorescent in situ hybridization and qPCR that the spectrum and angle of environmental light both influence the development of spectral sensitivity regions by altering the distribution and level of opsins across the retina. Normally, M. zebra coexpresses LWS opsin with RH2Aα opsin in double cones of the ventral but not the dorsal retina. However, when illuminated from below throughout development, adult M. zebra coexpressed LWS and RH2Aα in double cones both dorsally and ventrally. Thus, environmental background spectra alter the spectral sensitivity pattern that develops across the retina, potentially influencing behaviours and related evolutionary processes such as courtship and speciation. PMID:26175094

  11. Multispecies Outcomes of Sympatric Speciation after Admixture with the Source Population in Two Radiations of Nicaraguan Crater Lake Cichlids

    Science.gov (United States)

    Kautt, Andreas F.; Machado-Schiaffino, Gonzalo; Meyer, Axel

    2016-01-01

    The formation of species in the absence of geographic barriers (i.e. sympatric speciation) remains one of the most controversial topics in evolutionary biology. While theoretical models have shown that this most extreme case of primary divergence-with-gene-flow is possible, only a handful of accepted empirical examples exist. And even for the most convincing examples uncertainties remain; complex histories of isolation and secondary contact can make species falsely appear to have originated by sympatric speciation. This alternative scenario is notoriously difficult to rule out. Midas cichlids inhabiting small and remote crater lakes in Nicaragua are traditionally considered to be one of the best examples of sympatric speciation and lend themselves to test the different evolutionary scenarios that could lead to apparent sympatric speciation since the system is relatively small and the source populations known. Here we reconstruct the evolutionary history of two small-scale radiations of Midas cichlids inhabiting crater lakes Apoyo and Xiloá through a comprehensive genomic data set. We find no signs of differential admixture of any of the sympatric species in the respective radiations. Together with coalescent simulations of different demographic models our results support a scenario of speciation that was initiated in sympatry and does not result from secondary contact of already partly diverged populations. Furthermore, several species seem to have diverged simultaneously, making Midas cichlids an empirical example of multispecies outcomes of sympatric speciation. Importantly, however, the demographic models strongly support an admixture event from the source population into both crater lakes shortly before the onset of the radiations within the lakes. This opens the possibility that the formation of reproductive barriers involved in sympatric speciation was facilitated by genetic variants that evolved in a period of isolation between the initial founding

  12. Lake Tanganyika--a 'melting pot' of ancient and young cichlid lineages (Teleostei: Cichlidae)?

    Science.gov (United States)

    Weiss, Juliane D; Cotterill, Fenton P D; Schliewen, Ulrich K

    2015-01-01

    A long history of research focused on the East Africa cichlid radiations (EAR) revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tanganyika colonization scenarios. 3312 AFLP loci and the mitochondrial ND2 gene were genotyped for 91 species representing almost all major lacustrine and riverine haplotilapiine east African cichlid lineages with a focus on L. Tanganyika endemics. Explicitly testing for the possibility of ancient hybridisation events, a comprehensive phylogenetic network hypothesis is proposed for the origin and diversification of L. Tanganyika cichlids. Inference of discordant phylogenetic signal strongly suggests that the genomes of two endemic L. Tanganyika tribes, Eretmodini and Tropheini, are composed of an ancient mixture of riverine and lacustrine lineages. For the first time a strong monophyly signal of all non-haplochromine mouthbrooding species endemic to L. Tanganyika ("ancient mouthbrooders") was detected. Further, in the genomes of early diverging L. Tanganyika endemics Trematocarini, Bathybatini, Hemibatini and Boulengerochromis genetic components of other lineages belonging to the East African Radiation appear to be present. In combination with recent palaeo-geological results showing that tectonic activity in the L. Tanganyika region resulted in highly dynamic and heterogeneous landscape evolution over the Neogene and Pleistocene, the novel phylogenetic data render a single lacustrine basin as the geographical cradle of the endemic L. Tanganyika cichlid lineages unlikely. Instead a scenario of a pre-rift origin of several independent L. Tanganyika precursor lineages which

  13. Lake Tanganyika--a 'melting pot' of ancient and young cichlid lineages (Teleostei: Cichlidae?

    Directory of Open Access Journals (Sweden)

    Juliane D Weiss

    Full Text Available A long history of research focused on the East Africa cichlid radiations (EAR revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tanganyika colonization scenarios. 3312 AFLP loci and the mitochondrial ND2 gene were genotyped for 91 species representing almost all major lacustrine and riverine haplotilapiine east African cichlid lineages with a focus on L. Tanganyika endemics. Explicitly testing for the possibility of ancient hybridisation events, a comprehensive phylogenetic network hypothesis is proposed for the origin and diversification of L. Tanganyika cichlids. Inference of discordant phylogenetic signal strongly suggests that the genomes of two endemic L. Tanganyika tribes, Eretmodini and Tropheini, are composed of an ancient mixture of riverine and lacustrine lineages. For the first time a strong monophyly signal of all non-haplochromine mouthbrooding species endemic to L. Tanganyika ("ancient mouthbrooders" was detected. Further, in the genomes of early diverging L. Tanganyika endemics Trematocarini, Bathybatini, Hemibatini and Boulengerochromis genetic components of other lineages belonging to the East African Radiation appear to be present. In combination with recent palaeo-geological results showing that tectonic activity in the L. Tanganyika region resulted in highly dynamic and heterogeneous landscape evolution over the Neogene and Pleistocene, the novel phylogenetic data render a single lacustrine basin as the geographical cradle of the endemic L. Tanganyika cichlid lineages unlikely. Instead a scenario of a pre-rift origin of several independent L. Tanganyika precursor

  14. Complete mitochondrial DNA sequences of the threadfin cichlid (Petrochromis trewavasae and the blunthead cichlid (Tropheus moorii and patterns of mitochondrial genome evolution in cichlid fishes.

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    Christoph Fischer

    Full Text Available The cichlid fishes of the East African Great Lakes represent a model especially suited to study adaptive radiation and speciation. With several African cichlid genome projects being in progress, a promising set of closely related genomes is emerging, which is expected to serve as a valuable data base to solve questions on genotype-phenotype relations. The mitochondrial (mt genomes presented here are the first results of the assembly and annotation process for two closely related but eco-morphologically highly distinct Lake Tanganyika cichlids, Petrochromis trewavasae and Tropheus moorii. The genomic sequences comprise 16,588 bp (P. trewavasae and 16,590 bp (T. moorii, and exhibit the typical mitochondrial structure, with 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and a non-coding control region. Analyses confirmed that the two species are very closely related with an overall sequence similarity of 96%. We analyzed the newly generated sequences in the phylogenetic context of 21 published labroid fish mitochondrial genomes. Consistent with other vertebrates, the D-loop region was found to evolve faster than protein-coding genes, which in turn are followed by the rRNAs; the tRNAs vary greatly in the rate of sequence evolution, but on average evolve the slowest. Within the group of coding genes, ND6 evolves most rapidly. Codon usage is similar among examined cichlid tribes and labroid families; although a slight shift in usage patterns down the gene tree could be observed. Despite having a clearly different nucleotide composition, ND6 showed a similar codon usage. C-terminal ends of Cox1 exhibit variations, where the varying number of amino acids is related to the structure of the obtained phylogenetic tree. This variation may be of functional relevance for Cox1 synthesis.

  15. Comparative Osteology of the Suspensorial Complex of Algal-Feeding Cichlids (Pisces, Teleostei) from Lake Tanganyika

    OpenAIRE

    Yamaoka, Kosaku

    1988-01-01

    The comparative osteology of the suspensorial complex in 20 species of epilithic algal feeders from Lake Tanganyika was studied as a means of obtaining fundamental data for understanding the adaptive radiation in feeding habits of cichlid fishes in the East African lakes. Six types of suspensorial complex could be recognized within the 20 species studied. For the palatine, ectopterygoid, entopterygoid, metapterygoid, quadrate, symplectic, preoperculum and hyomandibula, 5, 2, 3, 3, 5, 2, 2 and...

  16. A hybrid genetic linkage map of two ecologically and morphologically divergent Midas cichlid fishes (Amphilophus spp.) obtained by massively parallel DNA sequencing (ddRADSeq).

    Science.gov (United States)

    Recknagel, Hans; Elmer, Kathryn R; Meyer, Axel

    2013-01-01

    Cichlid fishes are an excellent model system for studying speciation and the formation of adaptive radiations because of their tremendous species richness and astonishing phenotypic diversity. Most research has focused on African rift lake fishes, although Neotropical cichlid species display much variability as well. Almost one dozen species of the Midas cichlid species complex (Amphilophus spp.) have been described so far and have formed repeated adaptive radiations in several Nicaraguan crater lakes. Here we apply double-digest restriction-site associated DNA sequencing to obtain a high-density linkage map of an interspecific cross between the benthic Amphilophus astorquii and the limnetic Amphilophus zaliosus, which are sympatric species endemic to Crater Lake Apoyo, Nicaragua. A total of 755 RAD markers were genotyped in 343 F(2) hybrids. The map resolved 25 linkage groups and spans a total distance of 1427 cM with an average marker spacing distance of 1.95 cM, almost matching the total number of chromosomes (n = 24) in these species. Regions of segregation distortion were identified in five linkage groups. Based on the pedigree of parents to F(2) offspring, we calculated a genome-wide mutation rate of 6.6 × 10(-8) mutations per nucleotide per generation. This genetic map will facilitate the mapping of ecomorphologically relevant adaptive traits in the repeated phenotypes that evolved within the Midas cichlid lineage and, as the first linkage map of a Neotropical cichlid, facilitate comparative genomic analyses between African cichlids, Neotropical cichlids and other teleost fishes. PMID:23316439

  17. Females of an African cichlid fish display male-typical social dominance behavior and elevated androgens in the absence of males.

    Science.gov (United States)

    Renn, Suzy C P; Fraser, Eleanor J; Aubin-Horth, Nadia; Trainor, Brian C; Hofmann, Hans A

    2012-04-01

    Social environment can affect the expression of sex-typical behavior in both males and females. Males of the African cichlid species Astatotilapia burtoni have long served as a model system to study the neural, endocrine, and molecular basis of socially plastic dominance behavior. Here we show that in all-female communities of A. burtoni, some individuals acquire a male-typical dominance phenotype, including aggressive territorial defense, distinctive color patterns, and courtship behavior. Furthermore, dominant females have higher levels of circulating androgens than either subordinate females or females in mixed-sex communities. These male-typical traits do not involve sex change, nor do the social phenotypes in all-female communities differ in relative ovarian size, suggesting that factors other than gonadal physiology underlie much of the observed variation. In contrast to the well-studied situation in males, dominant and subordinate females do not differ in the rate of somatic growth. Dominant females are not any more likely than subordinates to spawn with an introduced male, although they do so sooner. These results extend the well known extraordinary behavioral plasticity of A. burtoni to the females of this species and provide a foundation for uncovering the neural and molecular basis of social dominance behavior while controlling for factors such as sex, gonadal state and growth. PMID:22285646

  18. Parallel evolution in Ugandan crater lakes: repeated evolution of limnetic body shapes in haplochromine cichlid fish

    OpenAIRE

    Machado-Schiaffino, Gonzalo; Kautt, Andreas F; Kusche, Henrik; Meyer, Axel

    2015-01-01

    Background The enormous diversity found in East African cichlid fishes in terms of morphology, coloration, and behavior have made them a model for the study of speciation and adaptive evolution. In particular, haplochromine cichlids, by far the most species-rich lineage of cichlids, are a well-known textbook example for parallel evolution. Southwestern Uganda is an area of high tectonic activity, and is home to numerous crater lakes. Many Ugandan crater lakes were colonized, apparently indepe...

  19. Tol2-mediated generation of a transgenic haplochromine cichlid, Astatotilapia burtoni.

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    Scott A Juntti

    Full Text Available Cichlid fishes represent one of the most species-rich and rapid radiations of a vertebrate family. These ~2200 species, predominantly found in the East African Great Lakes, exhibit dramatic differences in anatomy, physiology, and behavior. However, the genetic bases for this radiation, and for the control of their divergent traits, are unknown. A flood of genomic and transcriptomic data promises to suggest mechanisms underlying the diversity, but transgenic technology will be needed to rigorously test the hypotheses generated. Here we demonstrate the successful use of the Tol2 transposon system to generate transgenic Astatotilapia burtoni, a haplochromine cichlid from Lake Tanganyika, carrying the GFP transgene under the control of the ubiquitous EF1α promoter. The transgene integrates into the genome, is successfully passed through the germline, and the widespread GFP expression pattern is stable across siblings and multiple generations. The stable inheritance and expression patterns indicate that the Tol2 system can be applied to generate A. burtoni transgenic lines. Transgenesis has proven to be a powerful technology for manipulating genes and cells in other model organisms and we anticipate that transgenic A. burtoni and other cichlids will be used to test the mechanisms underlying behavior and speciation.

  20. Phenotypic plasticity and heterochrony in Cichlasoma managuense (Pisces, Cichlidae) and their implications for speciation in cichlid fishes

    OpenAIRE

    Meyer, Axel

    1987-01-01

    Cichlid fishes in African rift lakes have undergone rapid speciation, resulting in "species flocks" with more than 300 endemic species in some of the lakes. Most researchers assume that there is little phenotypic variation in cichlid fishes. I report here extensive phenotypic plasticity in a Neotropical cichlid species. I examined the influence of diet on trophic morphology during ontogeny in Cichlasonia managuense. Two groups of full siblings were fed two different diets for eight months aft...

  1. Nuclear markers reveal unexpected genetic variation and a Congolese-Nilotic origin of the Lake Victoria cichlid species flock.

    Science.gov (United States)

    Seehausen, Ole; Koetsier, Egbert; Schneider, Maria Victoria; Chapman, Lauren J; Chapman, Colin A; Knight, Mairi E; Turner, George F; van Alphen, Jacques J M; Bills, Roger

    2003-01-22

    Phylogenetic analyses based on mitochondrial (mt) DNA have indicated that the cichlid species flock of the Lake Victoria region is derived from a single ancestral species found in East African rivers, closely related to the ancestor of the Lake Malawi cichlid species flock. The Lake Victoria flock contains ten times less mtDNA variation than the Lake Malawi radiation, consistent with current estimates of the ages of the lakes. We present results of a phylogenetic investigation using nuclear (amplified fragment length polymorphism) markers and a wider coverage of riverine haplochromines. We demonstrate that the Lake Victoria-Edward flock is derived from the morphologically and ecologically diverse cichlid genus Thoracochromis from the Congo and Nile, rather than from the phenotypically conservative East African Astatotilapia. This implies that the ability to express much of the morphological diversity found in the species flock may by far pre-date the origin of the flock. Our data indicate that the nuclear diversity of the Lake Victoria-Edward species flock is similar to that of the Lake Malawi flock, indicating that the genetic diversity is considerably older than the 15 000 years that have passed since the lake began to refill. Most of this variation is manifested in trans-species polymorphisms, indicating very recent cladogenesis from a genetically very diverse founder stock. Our data do not confirm strict monophyly of either of the species flocks, but raise the possibility that these flocks have arisen from hybrid swarms. PMID:12590750

  2. Assortative mating among Lake Malawi cichlid fish populations is not simply predictable from male nuptial colour

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    Taylor Martin I

    2009-03-01

    Full Text Available Abstract Background Research on the evolution of reproductive isolation in African cichlid fishes has largely focussed on the role of male colours and female mate choice. Here, we tested predictions from the hypothesis that allopatric divergence in male colour is associated with corresponding divergence in preference. Methods We studied four populations of the Lake Malawi Pseudotropheus zebra complex. We predicted that more distantly-related populations that independently evolved similar colours would interbreed freely while more closely-related populations with different colours mate assortatively. We used microsatellite genotypes or mesh false-floors to assign paternity. Fisher's exact tests as well as Binomial and Wilcoxon tests were used to detect if mating departed from random expectations. Results Surprisingly, laboratory mate choice experiments revealed significant assortative mating not only between population pairs with differently coloured males, but between population pairs with similarly-coloured males too. This suggested that assortative mating could be based on non-visual cues, so we further examined the sensory basis of assortative mating between two populations with different male colour. Conducting trials under monochromatic (orange light, intended to mask the distinctive male dorsal fin hues (blue v orange of these populations, did not significantly affect the assortative mating by female P. emmiltos observed under control conditions. By contrast, assortative mating broke down when direct contact between female and male was prevented. Conclusion We suggest that non-visual cues, such as olfactory signals, may play an important role in mate choice and behavioural isolation in these and perhaps other African cichlid fish. Future speciation models aimed at explaining African cichlid radiations may therefore consider incorporating such mating cues in mate choice scenarios.

  3. Adaptive responses to environmental changes in Lake Victoria cichlids

    OpenAIRE

    Rijssel, Jacobus Cornelis van (Jacco)

    2014-01-01

    Lake Victoria cichlids show the fastest vertebrate adaptive radiation known which is why they function as a model organism to study evolution. In the past 40 years, Lake Victoria experienced severe environmental changes including the boom of the introduced, predatory Nile perch and eutrophication. Both environmental changes resulted in a decline of haplochromine cichlid species and numbers during the 1980s. However, during the 1990s and 2000s, some haplochromine species recovered. With the us...

  4. Rapid radiation, ancient incomplete lineage sorting and ancient hybridization in the endemic Lake Tanganyika cichlid tribe Tropheini.

    Science.gov (United States)

    Koblmüller, Stephan; Egger, Bernd; Sturmbauer, Christian; Sefc, Kristina M

    2010-04-01

    The evolutionary history of the endemic Lake Tanganyika cichlid tribe Tropheini, the sister group of the species flocks of Lake Malawi and the Lake Victoria region, was reconstructed from 2009 bp DNA sequence of two mitochondrial genes (ND2 and control region) and from 1293 AFLP markers. A period of rapid cladogenesis at the onset of the diversification of the Tropheini produced a multitude of specialized, predominantly rock-dwelling aufwuchs-feeders that now dominate in Lake Tanganyika's shallow habitat. Nested within the stenotopic rock-dwellers is a monophyletic group of species, which also utilize more sediment-rich habitat. Most of the extant species date back to at least 0.7 million years ago. Several instances of disagreement between AFLP and mtDNA tree topology are attributed to ancient incomplete lineage sorting, introgression and hybridization. A large degree of correspondence between AFLP clustering and trophic types indicated fewer cases of parallel evolution of trophic ecomorphology than previously inferred from mitochondrial data. PMID:19853055

  5. Hidden biodiversity in an ancient lake: phylogenetic congruence between Lake Tanganyika tropheine cichlids and their monogenean flatworm parasites

    OpenAIRE

    Vanhove, Maarten p. m.; Antoine Pariselle; Maarten Van Steenberge; Raeymaekers, Joost A. M.; Hablützel, Pascal I; Céline Gillardin; Bart Hellemans; Floris C Breman; Stephan Koblmüller; Christian Sturmbauer; Jos Snoeks; Filip A M Volckaert; Tine Huyse

    2015-01-01

    The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the bod...

  6. Mitochondrial phylogeny and phylogeography of East African squeaker catfishes (Siluriformes: Synodontis

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    Meyer Axel

    2006-06-01

    Full Text Available Abstract Background Squeaker catfishes (Pisces, Mochokidae, Synodontis are widely distributed throughout Africa and inhabit a biogeographic range similar to that of the exceptionally diverse cichlid fishes, including the three East African Great Lakes and their surrounding rivers. Since squeaker catfishes also prefer the same types of habitats as many of the cichlid species, we hypothesized that the East African Synodontis species provide an excellent model group for comparative evolutionary and phylogeographic analyses. Results Our analyses reveal the existence of six major lineages of Synodontis in East Africa that diversified about 20 MYA from a Central and/or West African ancestor. The six lineages show a clear geographic patterning. Two lineages are endemic to Lake Tanganyika (plus one non-endemic representative, and these are the only two Synodontis lineages that diversified further into a small array of species. One of these species is the cuckoo catfish (S. multipunctatus, a unique brood parasite of mouthbrooding haplochromine cichlids, which seems to have evolved in parallel with the radiation of its cichlid host lineage, the Tropheini. We also detect an accelerated rate of molecular evolution in S. multipunctatus, which might be the consequence of co-evolutionary dynamics. Conclusion We conclude that the ancestral lineage of today's East African squeaker catfish fauna has colonized the area before the Great Lakes have formed. This ancestor diversified rapidly into at least six lineages that inhabit lakes and rivers in East Africa. Lake Tanganyika is the only lake harboring a small species flock of squeaker catfishes.

  7. Colour forms of Amazonian cichlid fish represent reproductively isolated species.

    Science.gov (United States)

    Ready, J S; Sampaio, I; Schneider, H; Vinson, C; Dos Santos, T; Turner, G F

    2006-07-01

    Laboratory mate choice experiments have confirmed species status for cichlid fish in the African Great Lakes that differ in colour and little else. Colour differences between allopatric populations of the South American cichlid genus Apistogramma are known for many species, yet the status of such populations has not been previously tested. Analysis of the genetic relationships and mate choice characteristics of populations previously described as Apistogramma caetei from eastern Amazonia indicates genetic differentiation into at least three allopatric lineages, which also show strong prezygotic isolation through female mate choice, confirming them as Biological species. If future studies confirm that this result is indicative of a general trend, the species richness of the South American cichlid fishes may presently be seriously underestimated. PMID:16780514

  8. Identification of cichlid fishes from Lake Malawi using computer vision.

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    Deokjin Joo

    Full Text Available BACKGROUND: The explosively radiating evolution of cichlid fishes of Lake Malawi has yielded an amazing number of haplochromine species estimated as many as 500 to 800 with a surprising degree of diversity not only in color and stripe pattern but also in the shape of jaw and body among them. As these morphological diversities have been a central subject of adaptive speciation and taxonomic classification, such high diversity could serve as a foundation for automation of species identification of cichlids. METHODOLOGY/PRINCIPAL FINDING: Here we demonstrate a method for automatic classification of the Lake Malawi cichlids based on computer vision and geometric morphometrics. For this end we developed a pipeline that integrates multiple image processing tools to automatically extract informative features of color and stripe patterns from a large set of photographic images of wild cichlids. The extracted information was evaluated by statistical classifiers Support Vector Machine and Random Forests. Both classifiers performed better when body shape information was added to the feature of color and stripe. Besides the coloration and stripe pattern, body shape variables boosted the accuracy of classification by about 10%. The programs were able to classify 594 live cichlid individuals belonging to 12 different classes (species and sexes with an average accuracy of 78%, contrasting to a mere 42% success rate by human eyes. The variables that contributed most to the accuracy were body height and the hue of the most frequent color. CONCLUSIONS: Computer vision showed a notable performance in extracting information from the color and stripe patterns of Lake Malawi cichlids although the information was not enough for errorless species identification. Our results indicate that there appears an unavoidable difficulty in automatic species identification of cichlid fishes, which may arise from short divergence times and gene flow between closely related species.

  9. Sensory basis for detection of benthic prey in two Lake Malawi cichlids.

    Science.gov (United States)

    Schwalbe, Margot A B; Webb, Jacqueline F

    2014-04-01

    The adaptive radiations of African cichlids resulted in a diversity of feeding morphologies and strategies, but the role of sensory biology in prey detection and feeding ecology remains largely unexplored. Two endemic Lake Malawi cichlid genera, Tramitichromis and Aulonocara, feed on benthic invertebrates, but differ in lateral line morphology (narrow and widened lateral line canals, respectively) and foraging strategy. The hypothesis that they use their lateral line systems differently was tested by looking at the relative contribution of the lateral line system and vision in prey detection by Tramitichromis sp. and comparing results to those from a complementary study using Aulonocara stuartgranti (Schwalbe et al., 2012). First, behavioral trials were used to assess the ability of Tramitichromis sp. to detect live (mobile) and dead (immobile) benthic prey under light and dark conditions. Second, trials were run before, immediately after, and several weeks after chemical ablation of the lateral line system to determine its role in feeding behavior. Results show that Tramitichromis sp. is a visual predator that neither locates prey in the dark nor depends on lateral line input for prey detection and is thus distinct from A. stuartgranti, which uses its lateral line or a combination of vision and lateral line to detect prey depending on light condition. Investigating how functionally distinctive differences in sensory morphology are correlated with feeding behavior in the laboratory and determining the role of sensory systems in feeding ecology will provide insights into how sensory capabilities may contribute to trophic niche segregation. PMID:24369759

  10. Out of Tanganyika: Genesis, explosive speciation, key-innovations and phylogeography of the haplochromine cichlid fishes

    OpenAIRE

    Verheyen Erik; Mack Tanja; Salzburger Walter; Meyer Axel

    2005-01-01

    BackgroundThe adaptive radiations of cichlid fishes in East Africa are well known for their spectacular diversity and their astonishingly fast rates of speciation. About 80% of all 2,500 cichlid species in East Africa, and virtually all cichlid species from Lakes Victoria (~500 species) and Malawi (~1,000 species) are haplochromines. Here, we present the most extensive phylogenetic and phylogeographic analysis so far that includes about 100 species and is based on about 2,000 bp of the mitoch...

  11. Tempo and mode of diversification of lake Tanganyika cichlid fishes.

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    Julia J Day

    Full Text Available BACKGROUND: Understanding the causes of disparities in species diversity across taxonomic groups and regions is a fundamental aim in evolutionary biology. Addressing these questions is difficult because of the need for densely sampled phylogenies and suitable empirical systems. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigate the cichlid fish radiation of Lake Tanganyika and show that per lineage diversification rates have been more than six times slower than in the species flocks of Lakes Victoria and Malawi. The result holds even at peak periods of diversification in Lake Tanganyika, ruling out the age of the lake as an explanation for slow average rates, and is robust to uncertainties over the calibration of cichlid radiations in geological time. Moreover, Lake Tanganyika lineages, irrespective of different biological characteristics (e.g. sexually dichromatic versus sexually monochromatic clades, have diversified at similar rates, falling within typical estimates across a range of plant and animal clades. For example, the mostly sexually dichromatic haplochromines, which have speciated explosively in Lakes Victoria and Malawi, have displayed modest rates in Lake Tanganyika (where they are called Tropheini. CONCLUSION/SIGNIFICANCE: Our results show that either the Lake Tanganyika environment is less conducive for cichlid speciation or the remarkable diversifying abilities of the haplochromines were inhibited by the prior occupancy of older radiations. Although the results indicate a dominant role for the environment in shaping cichlid diversification, differences in the timing of diversification among the Tanganyikan tribes indicate that biological differences were still important for the dynamics of species build-up in the lake. While we cannot resolve the timing of the radiation relative to the origin of the lake, because of the lack of robust geological date calibrations for cichlids, our results are consistent with a scenario that the

  12. A tribal level phylogeny of Lake Tanganyika cichlid fishes based on a genomic multi-marker approach

    OpenAIRE

    Meyer, Britta S.; Matschiner, Michael; Salzburger, Walter

    2015-01-01

    Highlights: • We provide a new phylogeny for Lake Tanganyika cichlids using 42 nuclear makers. • Data concatenation and a Bayesian concordance analysis lead to congruent results. • Gene tree discordance hints to past hybridization or incomplete lineage sorting. • The Lamprologini are the sister-group to the ‘H-lineage’. • The Eretmodini are nested within the ‘H-lineage’. Abstract: The species-flocks of cichlid fishes in the East African Great Lakes Victoria, Malawi and ...

  13. Eco-morphological differentiation in Lake Magadi tilapia, an extremophile cichlid fish living in hot, alkaline and hypersaline lakes in East Africa.

    Science.gov (United States)

    Kavembe, Geraldine D; Kautt, Andreas F; Machado-Schiaffino, Gonzalo; Meyer, Axel

    2016-04-01

    Ecological diversification through divergent selection is thought to be a major force during the process of adaptive radiations. However, the large sizes and complexity of most radiations such as those of the cichlids in the African Great Lakes make it impossible to infer the exact evolutionary history of any population divergence event. The genus Alcolapia, a small cichlid lineage endemic to Lakes Magadi and Natron in East Africa, exhibits phenotypes similar to some of those found in cichlids of the radiations of the African Great Lakes. The simplicity within Alcolapia makes it an excellent model system to investigate ecological diversification and speciation. We used an integrated approach including population genomics based on RAD-seq data, geometric morphometrics and stable isotope analyses to investigate the eco-morphological diversification of tilapia in Lake Magadi and its satellite lake Little Magadi. Additionally, we reconstructed the demographic history of the species using coalescent simulations based on the joint site frequency spectrum. The population in Little Magadi has a characteristically upturned mouth-possibly an adaptation to feeding on prey from the water surface. Eco-morphological differences between populations within Lake Magadi are more subtle, but are consistent with known ecological differences between its lagoons such as high concentrations of nitrogen attributable to extensive guano deposits in Rest of Magadi relative to Fish Springs Lagoon. All populations diverged simultaneously only about 1100 generations ago. Differences in levels of gene flow between populations and the effective population sizes have likely resulted in the inferred heterogeneous patterns of genome-wide differentiation. PMID:26547282

  14. Evolution of cichlid vision via trans-regulatory divergence

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    O’Quin Kelly E

    2012-12-01

    Full Text Available Abstract Background Phenotypic evolution may occur through mutations that affect either the structure or expression of protein-coding genes. Although the evolution of color vision has historically been attributed to structural mutations within the opsin genes, recent research has shown that opsin regulatory mutations can also tune photoreceptor sensitivity and color vision. Visual sensitivity in African cichlid fishes varies as a result of the differential expression of seven opsin genes. We crossed cichlid species that express different opsin gene sets and scanned their genome for expression Quantitative Trait Loci (eQTL responsible for these differences. Our results shed light on the role that different structural, cis-, and trans-regulatory mutations play in the evolution of color vision. Results We identified 11 eQTL that contribute to the divergent expression of five opsin genes. On three linkage groups, several eQTL formed regulatory “hotspots” associated with the expression of multiple opsins. Importantly, however, the majority of the eQTL we identified (8/11 or 73% occur on linkage groups located trans to the opsin genes, suggesting that cichlid color vision has evolved primarily via trans-regulatory divergence. By modeling the impact of just two of these trans-regulatory eQTL, we show that opsin regulatory mutations can alter cichlid photoreceptor sensitivity and color vision at least as much as opsin structural mutations can. Conclusions Combined with previous work, we demonstrate that the evolution of cichlid color vision results from the interplay of structural, cis-, and especially trans-regulatory loci. Although there are numerous examples of structural and cis-regulatory mutations that contribute to phenotypic evolution, our results suggest that trans-regulatory mutations could contribute to phenotypic divergence more commonly than previously expected, especially in systems like color vision, where compensatory changes in the

  15. Parsing parallel evolution: ecological divergence and differential gene expression in the adaptive radiations of thick-lipped Midas cichlid fishes from Nicaragua.

    Science.gov (United States)

    Manousaki, Tereza; Hull, Pincelli M; Kusche, Henrik; Machado-Schiaffino, Gonzalo; Franchini, Paolo; Harrod, Chris; Elmer, Kathryn R; Meyer, Axel

    2013-02-01

    The study of parallel evolution facilitates the discovery of common rules of diversification. Here, we examine the repeated evolution of thick lips in Midas cichlid fishes (the Amphilophus citrinellus species complex)-from two Great Lakes and two crater lakes in Nicaragua-to assess whether similar changes in ecology, phenotypic trophic traits and gene expression accompany parallel trait evolution. Using next-generation sequencing technology, we characterize transcriptome-wide differential gene expression in the lips of wild-caught sympatric thick- and thin-lipped cichlids from all four instances of repeated thick-lip evolution. Six genes (apolipoprotein D, myelin-associated glycoprotein precursor, four-and-a-half LIM domain protein 2, calpain-9, GTPase IMAP family member 8-like and one hypothetical protein) are significantly underexpressed in the thick-lipped morph across all four lakes. However, other aspects of lips' gene expression in sympatric morphs differ in a lake-specific pattern, including the magnitude of differentially expressed genes (97-510). Generally, fewer genes are differentially expressed among morphs in the younger crater lakes than in those from the older Great Lakes. Body shape, lower pharyngeal jaw size and shape, and stable isotopes (δ(13)C and δ(15)N) differ between all sympatric morphs, with the greatest differentiation in the Great Lake Nicaragua. Some ecological traits evolve in parallel (those related to foraging ecology; e.g. lip size, body and head shape) but others, somewhat surprisingly, do not (those related to diet and food processing; e.g. jaw size and shape, stable isotopes). Taken together, this case of parallelism among thick- and thin-lipped cichlids shows a mosaic pattern of parallel and nonparallel evolution. PMID:23057963

  16. Developmental basis of phenotypic integration in two Lake Malawi cichlids

    OpenAIRE

    Le Pabic, Pierre; Cooper, W. James; Schilling, Thomas F.

    2016-01-01

    Background Cichlid fishes from the Rift Lakes of East Africa have undergone the most spectacular adaptive radiations in vertebrate history. Eco-morphological adaptations in lakes Victoria, Malawi and Tanganyika have resulted in a vast array of skull shapes and sizes, yet primary axes of morphological variation are conserved in all three radiations, prominently including the size of the preorbital region of the skull. This conserved pattern suggests that development may constrain the trajector...

  17. New record of a fossil haplotilapiine cichlid from Central Kenya

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    Stefanie B. R. Penk

    2015-11-01

    Full Text Available African freshwater cichlids (Cichlidae: Pseudocrenilabrinae are well known for their exceptionally great diversity and their capability of rapid speciation as well as diverse adaptations. The extant Pseudocrenilabrinae can be grouped into 27 tribes, with more than 2000 species harbored in the Great Lakes and surrounding water bodies of the East African Rift System. However, this unique diversity is not reflected in the fossil record because fossil cichlids were predominantly reported based on isolated teeth and bones. Moreover, the few articulated specimens that are known have not been analyzed sufficiently with regard to their systematic position due to lack of comparative material. Here we present a new extraordinarily well-preserved cichlid fish fossil from the Middle Miocene (c. 12.5 Ma Lagerstaette Kabchore, which was recovered during recent fieldwork in the Tugen Hills (Baringo County, Central Kenya Rift. Based on the evidence of tricuspid teeth, the Kabchore fossil can be assigned to the subclade of the Haplotilapiines within the Pseudocrenilabrinae. The multivariate analysis of a large meristic data set, derived from 1014 extant specimens (encompassing all main lineages of Haplotilapiines and usage of available osteological data suggest that this fossil is most likely related to one of the three haplotilapiine tribes Tilapiini, Haplochromini or Oreochromini. Moreover, the fossil specimen closely resembles the extinct cichlid Oreochromis martyni (Van Couvering, 1982, previously described as species of Sarotherodon from the Middle Miocene alkaline Kapkiamu Lake in the Tugen Hills. The analysis of the greatly preserved fossil fish specimen from Kabchore definitely supplements the fragmentary fossil record of Africa’s Cichlidae and will afford new insights into its evolutionary history. We also expect that this fossil will be useful as calibration point for new divergence-time estimates.

  18. A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids.

    Science.gov (United States)

    McGee, Matthew D; Borstein, Samuel R; Neches, Russell Y; Buescher, Heinz H; Seehausen, Ole; Wainwright, Peter C

    2015-11-27

    Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion. PMID:26612951

  19. Genetic isolation and morphological divergence mediated by high-energy rapids in two cichlid genera from the lower Congo rapids

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    Stiassny Melanie LJ

    2010-05-01

    Full Text Available Abstract Background It is hypothesized that one of the mechanisms promoting diversification in cichlid fishes in the African Great Lakes has been the well-documented pattern of philopatry along shoreline habitats leading to high levels of genetic isolation among populations. However lake habitats are not the only centers of cichlid biodiversity - certain African rivers also contain large numbers of narrowly endemic species. Patterns of isolation and divergence in these systems have tended to be overlooked and are not well understood. Results We examined genetic and morphological divergence among populations of two narrowly endemic cichlid species, Teleogramma depressum and Lamprologus tigripictilis, from a 100 km stretch of the lower Congo River using both nDNA microsatellites and mtDNA markers along with coordinate-based morphological techniques. In L. tigripictilis, the strongest genetic break was concordant with measurable phenotypic divergence but no morphological disjunction was detected for T. depressum despite significant differentiation at mtDNA and nDNA microsatellite markers. Conclusions The genetic markers revealed patterns of philopatry and estimates of genetic isolation that are among the highest reported for any African cichlid species over a comparable geographic scale. We hypothesize that the high levels of philopatry observed are generated and maintained by the extreme hydrology of the lower Congo River.

  20. Diet disparity among sympatric herbivorous cichlids in the same ecomorphs in Lake Tanganyika: amplicon pyrosequences on algal farms and stomach contents

    OpenAIRE

    Hata, Hiroki; Akifumi S Tanabe; Yamamoto, Satoshi; Toju, Hirokazu; Kohda, Masanori; Hori, Michio

    2014-01-01

    Background Lake Tanganyika, an ancient lake in the Great Rift Valley, is famous for the adaptive radiation of cichlids. Five tribes of the Cichlidae family have acquired herbivory, with five ecomorphs: grazers, browsers, scrapers, biters and scoopers. Sixteen species of the herbivorous cichlids coexist on a rocky littoral slope in the lake. Seven of them individually defend feeding territories against intruding herbivores to establish algal farms. We collected epiphyton from these territories...

  1. Time and Origin of Cichlid Colonization of the Lower Congo Rapids

    OpenAIRE

    Julia Schwarzer; Bernhard Misof; Ifuta, Seraphin N.; Schliewen, Ulrich K.

    2011-01-01

    Most freshwater diversity is arguably located in networks of rivers and streams, but, in contrast to lacustrine systems riverine radiations, are largely understudied. The extensive rapids of the lower Congo River is one of the few river stretches inhabited by a locally endemic cichlid species flock as well as several species pairs, for which we provide evidence that they have radiated in situ. We use more that 2,000 AFLP markers as well as multilocus sequence datasets to reconstruct their ori...

  2. Cichlid fishes as a model to understand normal and clinical craniofacial variation.

    Science.gov (United States)

    Powder, Kara E; Albertson, R Craig

    2016-07-15

    We have made great strides towards understanding the etiology of craniofacial disorders, especially for 'simple' Mendelian traits. However, the facial skeleton is a complex trait, and the full spectrum of genetic, developmental, and environmental factors that contribute to its final geometry remain unresolved. Forward genetic screens are constrained with respect to complex traits due to the types of genes and alleles commonly identified, developmental pleiotropy, and limited information about the impact of environmental interactions. Here, we discuss how studies in an evolutionary model - African cichlid fishes - can complement traditional approaches to understand the genetic and developmental origins of complex shape. Cichlids exhibit an unparalleled range of natural craniofacial morphologies that model normal human variation, and in certain instances mimic human facial dysmorphologies. Moreover, the evolutionary history and genomic architecture of cichlids make them an ideal system to identify the genetic basis of these phenotypes via quantitative trait loci (QTL) mapping and population genomics. Given the molecular conservation of developmental genes and pathways, insights from cichlids are applicable to human facial variation and disease. We review recent work in this system, which has identified lbh as a novel regulator of neural crest cell migration, determined the Wnt and Hedgehog pathways mediate species-specific bone morphologies, and examined how plastic responses to diet modulate adult facial shapes. These studies have not only revealed new roles for existing pathways in craniofacial development, but have identified new genes and mechanisms involved in shaping the craniofacial skeleton. In all, we suggest that combining work in traditional laboratory and evolutionary models offers significant potential to provide a more complete and comprehensive picture of the myriad factors that are involved in the development of complex traits. PMID:26719128

  3. Antipredator responses by native mosquitofish to non-native cichlids: An examination of the role of prey naiveté

    Science.gov (United States)

    Rehage, Jennifer S.; Dunlop, Katherine L.; Loftus, William F.

    2009-01-01

    The strong impact of non-native predators in aquatic systems is thought to relate to the evolutionary naiveté of prey. Due to isolation and limited dispersal, this naiveté may be relatively high in freshwater systems. In this study, we tested this notion by examining the antipredator response of native mosquitofish, Gambusia holbrooki, to two non-native predators found in the Everglades, the African jewelfish,Hemichromis letourneuxi, and the Mayan cichlid, Cichlasoma urophthalmus. We manipulated prey naiveté by using two mosquitofish populations that varied in their experience with the recent invader, the African jewelfish, but had similar levels of experience with the longer-established Mayan cichlid. Specifically, we tested these predictions: (1) predator hunting modes differed between the two predators, (2) predation rates would be higher by the novel jewelfish predator, (3) particularly on the naive population living where jewelfish have not invaded yet, (4) antipredator responses would be stronger to Mayan cichlids due to greater experience and weaker and/or ineffective to jewelfish, and (5) especially weakest by the naive population. We assayed prey and predator behavior, and prey mortality in lab aquaria where both predators and prey were free-ranging. Predator hunting modes and habitat domains differed, with jewelfish being more active search predators that used slightly higher parts of the water column and less of the habitat structure relative to Mayan cichlids. In disagreement with our predictions, predation rates were similar between the two predators, antipredator responses were stronger to African jewelfish (except for predator inspections), and there was no difference in response between jewelfish-savvy and jewelfish-naive populations. These results suggest that despite the novelty of introduced predators, prey may be able to respond appropriately if non-native predator archetypes are similar enough to those of native predators, if prey rely

  4. Tenth national congress of the South African Society of Radiation Therapists

    International Nuclear Information System (INIS)

    The proceedings of the tenth national congress of the South African Society of Radiation Therapists are presented. Papers on the following topics were presented: gynaecological malignancies and oncology; pain and symptom control; radiobiology; radiotherapy of the head and neck; combined modality therapy, and lymphoma. Separate abstracts were prepared for thirty five of the papers presented. The remaining papers were considered outside the subject scope of INIS

  5. Correlated evolution of short wavelength sensitive photoreceptor sensitivity and color pattern in Lake Malawi cichlids

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    Michael J. Pauers

    2016-02-01

    Full Text Available For evolutionary ecologists, the holy grail of visual ecology is to establish an unambiguous link between photoreceptor sensitivity, the spectral environment, and the perception of specific visual stimuli (e.g., mates, food, predators, etc.. Due to the bright nuptial colors of the males, and the role female mate choice plays in their evolution, the haplochromine cichlid fishes of the African great lakes are favorite research subjects for such investigations. Despite this attention, current evidence is equivocal; while distinct correlations among photoreceptor sensitivity, photic environment, and male coloration exist in Lake Victorian haplochromines, attempts to find such correlations in Lake Malawian cichlids have failed. Lake Malawi haplochromines have a wide variability in their short-wavelength-sensitive photoreceptors, especially compared to their mid- and long-wavelength-sensitive photoreceptors; these cichlids also vary in the degree to which they express one of three basic color patterns (vertical bars, horizontal stripes, and solid patches of colors, each of which is likely used in a different form of communication. Thus, we hypothesize that, in these fishes, spectral sensitivity and color pattern have evolved in a correlated fashion to maximize visual communication; specifically, ultraviolet sensitivity should be found in vertically-barred species to promote ‘private’ communication, while striped species should be less likely to have ultraviolet sensitivity, since their color pattern carries ‘public’ information. Using phylogenetic independent contrasts, we found that barred species had strong sensitivity to ultraviolet wavelengths, but that striped species typically lacked sensitivity to ultraviolet light. Further, the only variable, even when environmental variables were simultaneously considered, that could predict ultraviolet sensitivity was color pattern. We also found that, using models of correlated evolution, color

  6. Chemical communication in cichlids: A mini-review.

    Science.gov (United States)

    Keller-Costa, Tina; Canário, Adelino V M; Hubbard, Peter C

    2015-09-15

    The family Cichlidae is well-known for pair-formation, parental care, territoriality, elaborate courtship and social organization. Do cichlids use chemical communication to mediate any of these behaviours? Early studies suggest that parent cichlids can discriminate between conspecific and heterospecific wrigglers (but not eggs) using olfactory cues. Some species are able to discriminate between their own brood and other conspecific broods based on olfaction. The young recognise conspecific adults (although not necessarily their parents) through the odorants they release. In both scenarios, protection of the young from predation is the likely selective force. Some male cichlids use urinary pheromones during courtship and spawning to attract females and induce ovulation. Females--in their turn--may base their mate-choice in part on assessment of those self-same pheromones. The same pheromonal system may be involved in establishing and maintaining the social hierarchies in lek-breeding cichlids. Individual recognition is also mediated by chemical communication. Finally, there is ample behavioural evidence that cichlids--like ostariophysan fish--release alarm cues that alert conspecifics to predation danger. Although the effects of these cues may be similar (e.g., increased shelter use, tighter schooling), they are different substances which remain to be identified. Cichlids, then, use chemical communication associated with many different behaviours. However, given the diversity of cichlids, little is known about the mechanisms of chemical communication or the chemical identity of the cues involved. The aim of this mini-review is to persuade those working with cichlids to consider the involvement of chemical communication, and those working in chemical communication to consider using cichlids. PMID:25622908

  7. Integrating cytogenetics and genomics in comparative evolutionary studies of cichlid fish

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    Mazzuchelli Juliana

    2012-09-01

    Full Text Available Abstract Background The availability of a large number of recently sequenced vertebrate genomes opens new avenues to integrate cytogenetics and genomics in comparative and evolutionary studies. Cytogenetic mapping can offer alternative means to identify conserved synteny shared by distinct genomes and also to define genome regions that are still not fine characterized even after wide-ranging nucleotide sequence efforts. An efficient way to perform comparative cytogenetic mapping is based on BAC clones mapping by fluorescence in situ hybridization. In this report, to address the knowledge gap on the genome evolution in cichlid fishes, BAC clones of an Oreochromis niloticus library covering the linkage groups (LG 1, 3, 5, and 7 were mapped onto the chromosomes of 9 African cichlid species. The cytogenetic mapping data were also integrated with BAC-end sequences information of O. niloticus and comparatively analyzed against the genome of other fish species and vertebrates. Results The location of BACs from LG1, 3, 5, and 7 revealed a strong chromosomal conservation among the analyzed cichlid species genomes, which evidenced a synteny of the markers of each LG. Comparative in silico analysis also identified large genomic blocks that were conserved in distantly related fish groups and also in other vertebrates. Conclusions Although it has been suggested that fishes contain plastic genomes with high rates of chromosomal rearrangements and probably low rates of synteny conservation, our results evidence that large syntenic chromosome segments have been maintained conserved during evolution, at least for the considered markers. Additionally, our current cytogenetic mapping efforts integrated with genomic approaches conduct to a new perspective to address important questions involving chromosome evolution in fishes.

  8. Hidden biodiversity in an ancient lake: phylogenetic congruence between Lake Tanganyika tropheine cichlids and their monogenean flatworm parasites.

    Science.gov (United States)

    Vanhove, Maarten P M; Pariselle, Antoine; Van Steenberge, Maarten; Raeymaekers, Joost A M; Hablützel, Pascal I; Gillardin, Céline; Hellemans, Bart; Breman, Floris C; Koblmüller, Stephan; Sturmbauer, Christian; Snoeks, Jos; Volckaert, Filip A M; Huyse, Tine

    2015-01-01

    The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the body surface and gills of fishes. In contrast to many other parasites, they depend only on a single host species to complete their lifecycle. Our spatially comprehensive combined nuclear-mitochondrial DNA dataset of the parasites covering almost all tropheine host species (N = 18), reveals species-rich parasite assemblages and shows consistent host-specificity. Statistical comparisons of host and parasite phylogenies based on distance and topology-based tests demonstrate significant congruence and suggest that host-switching is rare. Molecular rate evaluation indicates that species of Cichlidogyrus probably diverged synchronically with the initial radiation of the tropheines. They further diversified through within-host speciation into an overlooked species radiation. The unique life history and specialisation of certain parasite groups has profound evolutionary consequences. Hence, evolutionary parasitology adds a new dimension to the study of biodiversity hotspots like Lake Tanganyika. PMID:26335652

  9. Mating and Parental Care in Lake Tanganyika's Cichlids

    OpenAIRE

    Sefc, Kristina M

    2011-01-01

    Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parenta...

  10. Out of Tanganyika: Genesis, explosive speciation, key-innovations and phylogeography of the haplochromine cichlid fishes

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    Verheyen Erik

    2005-02-01

    Full Text Available Abstract Background The adaptive radiations of cichlid fishes in East Africa are well known for their spectacular diversity and their astonishingly fast rates of speciation. About 80% of all 2,500 cichlid species in East Africa, and virtually all cichlid species from Lakes Victoria (~500 species and Malawi (~1,000 species are haplochromines. Here, we present the most extensive phylogenetic and phylogeographic analysis so far that includes about 100 species and is based on about 2,000 bp of the mitochondrial DNA. Results Our analyses revealed that all haplochromine lineages are ultimately derived from Lake Tanganyika endemics. We find that the three most ancestral lineages of the haplochromines sensu lato are relatively species poor, albeit widely distributed in Africa, whereas a fourth newly defined lineage – the 'modern haplochromines' – contains an unparalleled diversity that makes up more than 7% of the worlds' ~25,000 teleost species. The modern haplochromines' ancestor, most likely a riverine generalist, repeatedly gave rise to similar ecomorphs now found in several of the species flocks. Also, the Tanganyikan Tropheini are derived from that riverine ancestor suggesting that they successfully re-colonized Lake Tanganyika and speciated in parallel to an already established cichlid adaptive radiation. In contrast to most other known examples of adaptive radiations, these generalist ancestors were derived from highly diverse and specialized endemics from Lake Tanganyika. A reconstruction of life-history traits revealed that in an ancestral lineage leading to the modern haplochromines the characteristic egg-spots on anal fins of male individuals evolved. Conclusion We conclude that Lake Tanganyika is the geographic and genetic cradle of all haplochromine lineages. In the ancestors of the replicate adaptive radiations of the 'modern haplochromines', behavioral (maternal mouthbrooding, morphological (egg-spots and sexually selected (color

  11. The Midas cichlid species complex : Incipient sympatric speciation in Nicaraguan cichlid fishes?

    OpenAIRE

    Barluenga, Marta; Meyer, Axel

    2004-01-01

    Sympatric speciation is a contentious concept, although theoretical models as well as empirical evidence support its relevance in evolutionary biology. The Midas cichlid species complex (Amphilophus citrinellus, labiatus, zaliosus) from several crater lakes in Nicaragua fits several of the key characteristics of a sympatric speciation model. In particular, in A. citrinellus (i) strong assortative mating on the basis of colour polymorphism and (ii) ecological differentiation based on morpholog...

  12. Radiative Effects of Saharan Mineral Dust Aerosols on the Structure of African Easterly Waves

    Science.gov (United States)

    Bercos-Hickey, E.; Nathan, T. R.; Chen, S. H.

    2014-12-01

    How Saharan mineral dust affects the structure of African easterly waves (AEWs) is an outstanding scientific question. Addressing this question is important because AEWs often serve as precursors to the development of tropical storms off of West Africa. In this study, the Weather Research and Forecasting Dust (WRFD) model is used to examine the radiative effects of Saharan dust on the structure of AEWs that occurred in July 1995. Two numerical experiments are conducted. The first (control) experiment uses the standard WRF model in the absence of dust. The second experiment is identical to the first, but includes the transport and radiative effects of dust. Dust is modeled by 12 continuity equations for dust-sized particles that represent the spectrum of mineral dust in the atmosphere. Analysis and comparison of the no-dust and dust experiments show that Saharan dust significantly affects the structure of AEWs. For example, a spectral density analysis of the AEWs shows that dust causes higher peak power during the 3 to 6 day period at 700mb. For the meridional wind over Dakar in West Africa, the dust causes the power to increase by about 82% and to shift to a lower frequency by about a half day. Covariance plots show spatial shifts, structural changes and magnitude differences in the AEWs between the dust and no dust experiments. Calculations show that the dust causes the maximum in momentum flux to increase by about 4%. The African easterly jet (AEJ) also shows changes between the dust and no dust experiments. Ongoing work includes quantifying the structural changes of AEWs and the AEJ.

  13. Monophyletic origin of Lake Victoria cichlid fishes suggested by mitochondrial DNA sequences.

    Science.gov (United States)

    Meyer, A; Kocher, T D; Basasibwaki, P; Wilson, A C

    1990-10-11

    Lake Victoria, together with its satellite lakes, harbours roughly 200 endemic forms of cichlid fishes that are classified as 'haplochromines' and yet the lake system is less than a million years old. This 'flock' has attracted attention because of the possibility that it evolved within the lake from one ancestral species and that biologists are thus presented with a case of explosive evolution. Within the past decade, however, morphology has increasingly emphasized the view that the flock may be polyphyletic. We sequenced up to 803 base pairs of mitochondrial DNA from 14 representative Victorian species and 23 additional African species. The flock seems to be monophyletic, and is more akin to that from Lake Malawi than to species from Lake Tanganyika; in addition, it contains less genetic variation than does the human species, and there is virtually no sharing of mitochondrial DNA types among species. These results confirm that the founding event was recent. PMID:2215680

  14. Prostate cancer in African-American men: outcome following radiation therapy with or without adjuvant androgen ablation

    International Nuclear Information System (INIS)

    Purpose: To compare the outcome of irradiated clinically localized prostate cancer in African-American and white patients. Methods and Materials: This was a retrospective review of 1,201 men, 116 African-American and 1,085 white, with T1-T3, N0/NX, M0 prostate cancer receiving external radiation between 1987 and 1996. Pretreatment characteristics, treatment parameters, and outcome (relapse or rising prostate-specific antigen [PSA] levels, local recurrence, metastatic relapse, and survival) were compared between the groups using univariate and multivariate statistical methods. Results: There were no significant differences between African-American and white patients in T-stage, Gleason score, prostatic acid phosphatase (PAP) level, and testosterone level. African-Americans had a significantly lower incidence of abnormal digital rectal findings and a proportionally higher incidence of obstructive urinary symptoms at presentation and tended to be somewhat younger. A major difference between the two groups was in the significantly higher PSA levels among African-Americans (median, 14 ng/ml) than among white patients (median, 9.5 ng/ml). This translated into a higher incidence of unfavorable disease according to our criteria (39% vs. 25%) among African-Americans and, thus, to the more frequent use of adjuvant androgen ablation and to somewhat higher radiation doses in these patients. With a median follow-up of 42 months the overall 6-year freedom from relapse for African-Americans was 63% compared to 61% for whites (p = 0.634). We found no significant differences in biochemical relapse rates between any subgroups of African-Americans and whites. Specifically, even patients who did not have androgen ablation, when stratified by PSA levels, had similar outcomes regardless of race. Likewise, local recurrence and metastasis rates were not significantly different between the two groups. Conclusions: Although African-American patients tend to have higher pretreatment PSA

  15. Phylogeography, colonization and population history of the Midas cichlid species complex (Amphilophus spp. in the Nicaraguan crater lakes

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    Meyer Axel

    2010-10-01

    Full Text Available Abstract Background Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex Amphilophus spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phylogeographic analysis of the complete Midas Cichlid species complex in Nicaragua (> 2000 individuals covering the entire distributional range, using two types of molecular markers (the mitochondrial DNA control region and 15 microsatellites. We investigated the majority of known lake populations of this species complex and reconstructed their colonization history in order to distinguish between alternative speciation scenarios. Results We found that the large lakes contain older and more diverse Midas Cichlid populations, while all crater lakes hold younger and genetically less variable species assemblages. The large lakes appear to have repeatedly acted as source populations for all crater lakes, and our data indicate that faunal exchange among crater lakes is extremely unlikely. Despite their very recent (often only a few thousand years old and common origin from the two large Nicaraguan lakes, all crater lake Midas Cichlid radiations underwent independent, but parallel, evolution, and comprise distinct genetic units. Indeed several of these crater lakes contain multiple genetically distinct incipient species that most likely arose through sympatric speciation. Several crater lake radiations can be traced back to a single ancestral line, but some appear to have more than one founding lineage. The timing of the colonization(s of each crater lake differs, although most of them occurred more (probably much more recently than 20,000 years ago. Conclusion The

  16. Genetic structure of pelagic and littoral cichlid fishes from Lake Victoria.

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    Miyuki Takeda

    Full Text Available The approximately 700 species of cichlids found in Lake Victoria in East Africa are thought to have evolved over a short period of time, and they represent one of the largest known examples of adaptive radiation. To understand the processes that are driving this spectacular radiation, we must determine the present genetic structure of these species and elucidate how this structure relates to the ecological conditions that caused their adaptation. We analyzed the genetic structure of two pelagic and seven littoral species sampled from the southeast area of Lake Victoria using sequences from the mtDNA control region and 12 microsatellite loci as markers. Using a Bayesian model-based clustering method to analyze the microsatellite data, we separated these nine species into four groups: one group composed of pelagic species and another three groups composed mainly of rocky-shore species. Furthermore, we found significant levels of genetic variation between species within each group at both marker loci using analysis of molecular variance (AMOVA, although the nine species often shared mtDNA haplotypes. We also found significant levels of genetic variation between populations within species. These results suggest that initial groupings, some of which appear to have been related to habitat differences, as well as divergence between species within groups took place among the cichlid species of Lake Victoria.

  17. The Utility of Geometric Morphometrics to Elucidate Pathways of Cichlid Fish Evolution

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    Michaela Kerschbaumer

    2011-01-01

    Full Text Available Fishes of the family Cichlidae are famous for their spectacular species flocks and therefore constitute a model system for the study of the pathways of adaptive radiation. Their radiation is connected to trophic specialization, manifested in dentition, head morphology, and body shape. Geometric morphometric methods have been established as efficient tools to quantify such differences in overall body shape or in particular morphological structures and meanwhile found wide application in evolutionary biology. As a common feature, these approaches define and analyze coordinates of anatomical landmarks, rather than traditional counts or measurements. Geometric morphometric methods have several merits compared to traditional morphometrics, particularly for the distinction and analysis of closely related entities. Cichlid evolutionary research benefits from the efficiency of data acquisition, the manifold opportunities of analyses, and the potential to visualize shape changes of those landmark-based methods. This paper briefly introduces to the concepts and methods of geometric morphometrics and presents a selection of publications where those techniques have been successfully applied to various aspects of cichlid fish diversification.

  18. Hybrid origin of a cichlid population in Lake Malawi: implications for genetic variation and species diversity.

    Science.gov (United States)

    Smith, Peter F; Konings, Ad; Kornfield, Irv

    2003-09-01

    The importance of species recognition to taxonomic diversity among Lake Malawi cichlids has been frequently discussed. Hybridization - the apparent breakdown of species recognition - has been observed sporadically among cichlids and has been viewed as both a constructive and a destructive force with respect to species diversity. Here we provide genetic evidence of a natural hybrid cichlid population with a unique colour phenotype and elevated levels of genetic variation. We discuss the potential evolutionary consequences of interspecific hybridization in Lake Malawi cichlids and propose that the role of hybridization in generating both genetic variability and species diversity of Lake Malawi cichlids warrants further consideration. PMID:12919487

  19. Mating and Parental Care in Lake Tanganyika's Cichlids

    Directory of Open Access Journals (Sweden)

    Kristina M. Sefc

    2011-01-01

    Full Text Available Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parental care patterns and sexual dimorphism. Notes on measures of sexual selection intensity and the difficulties of defining mating systems and estimating selection intensities at species level conclude the essay.

  20. Significant Impacts of Radiation Physics in the WRF Model on the Precipitation and Dynamics of the West African Monsoon

    OpenAIRE

    Li, R.; J. Jin; Wang, Shih-Yu; Gillies, R. R.

    2014-01-01

    Precipitation from the West African Monsoon (WAM) provides food security and supports the economy in the region. As a consequence of the intrinsic complexities of the WAM’s evolution, accurate simulations of the WAM and its precipitation regime, through the application of regional climate models, are challenging. We used the coupled Weather Research and Forecasting (WRF) and Community Land Model (CLM) to explore impacts of radiation physics on the precipitation and dynamics of the WAM. Our re...

  1. Evolution of a unique predatory feeding apparatus: functional anatomy, development and a genetic locus for jaw laterality in Lake Tanganyika scale-eating cichlids

    Directory of Open Access Journals (Sweden)

    Albertson R Craig

    2010-01-01

    Full Text Available Abstract Background While bilaterality is a defining characteristic of triploblastic animals, several assemblages have managed to break this symmetry in order to exploit the adaptive peaks garnered through the lateralization of behaviour or morphology. One striking example of an evolved asymmetry in vertebrates comes from a group of scale-eating cichlid fishes from Lake Tanganyika. Members of the Perissodini tribe of cichlid fishes have evolved dental and craniofacial asymmetries in order to more effectively remove scales from the left or right flanks of prey. Here we examine the evolution and development of craniofacial morphology and laterality among Lake Tanganyika scale-eating cichlids. Results Using both geometric and traditional morphometric methods we found that the craniofacial evolution in the Perissodini involved discrete shifts in skeletal anatomy that reflect differences in habitat preference and predation strategies. Further, we show that the evolutionary history of the Perissodini is characterized by an accentuation of craniofacial laterality such that certain taxa show elaborate sided differences in craniofacial shape consistent with the sub-partitioning of function between sides of the head during attacks. Craniofacial laterality in the scale-eating specialist Perissodus microlepis was found to be evident early in development and exhibited a unimodal distribution, which is contrary to the adult condition where jaw laterality has been described as a discrete, bimodal antisymmetry. Finally, using linkage and association analyses we identified a conserved locus for jaw handedness that segregates among East African cichlids. Conclusions We suggest that, during the evolution of the Perissodini, selection has accentuated a latent, genetically determined handedness of the craniofacial skeleton, enabling the evolution of jaw asymmetries in order to increase predation success. Continued work on the developmental genetic basis of

  2. Alternative Reproductive Tactics in the Shell-Brooding Lake Tanganyika Cichlid Neolamprologus brevis

    OpenAIRE

    Kazutaka Ota; Mitsuto Aibara; Masaya Morita; Satoshi Awata; Michio Hori; Masanori Kohda

    2012-01-01

    Alternative reproductive tactics (ARTs) are found in several Lake Tanganyika shell-brooding cichlids. Field studies were conducted in the Wonzye population to examine reproductive ecology and ARTs in the Lake Tanganyika shell-brooding cichlid Neolamprologus brevis. We discovered that this fish occurred in both rocky- and sandy-bottom habitats, but in rocky habitats, brood-caring females exclusively occurred in shell-patches that another cichlid species created. All N. brevis of both sexes in ...

  3. On the origin of Lake Malawi cichlid species: A population genetic analysis of divergence

    OpenAIRE

    Won, Yong-jin; Sivasundar, Arjun; Wang, Yong; Hey, Jody

    2005-01-01

    The cichlid fishes of Lake Malawi are famously diverse. However, phylogenetic and population genetic studies of their history have been difficult because of the great amount of genetic variation that is shared between species. We apply a recently developed method for fitting the “isolation with migration” divergence model to a data set of specially designed compound loci to develop portraits of cichlid species divergence. Outgroup sequences from a cichlid from Lake Tanganyika permit model par...

  4. An Evaluation of the Role of Sensory Drive in the Evolution of Lake Malawi Cichlid Fishes

    OpenAIRE

    Smith, Adam R.; Moira J. van Staaden; Carleton, Karen L.

    2012-01-01

    Although the cichlids of Lake Malawi are an important model system for the study of sensory evolution and sexual selection, the evolutionary processes linking these two phenomena remain unclear. Prior works have proposed that evolutionary divergence is driven by sensory drive, particularly as it applies to the visual system. While evidence suggests that sensory drive has played a role in the speciation of Lake Victoria cichlids, the findings from several lines of research on cichlids of Lake ...

  5. Repeated parallel evolution of parental care strategies within Xenotilapia, a genus of cichlid fishes from Lake Tanganyika.

    Directory of Open Access Journals (Sweden)

    Michael R Kidd

    Full Text Available The factors promoting the evolution of parental care strategies have been extensively studied in experiment and theory. However, most attempts to examine parental care in an evolutionary context have evaluated broad taxonomic categories. The explosive and recent diversifications of East African cichlid fishes offer exceptional opportunities to study the evolution of various life history traits based on species-level phylogenies. The Xenotilapia lineage within the endemic Lake Tanganyika cichlid tribe Ectodini comprises species that display either biparental or maternal only brood care and hence offers a unique opportunity to study the evolution of distinct parental care strategies in a phylogenetic framework. In order to reconstruct the evolutionary relationships among 16 species of this lineage we scored 2,478 Amplified Fragment Length Polymorphisms (AFLPs across the genome. We find that the Ectodini genus Enantiopus is embedded within the genus Xenotilapia and that during 2.5 to 3 million years of evolution within the Xenotilapia clade there have been 3-5 transitions from maternal only to biparental care. While most previous models suggest that uniparental care (maternal or paternal arose from biparental care, we conclude from our species-level analysis that the evolution of parental care strategies is not only remarkably fast, but much more labile than previously expected.

  6. Species of Gyrodactylus von Nordmann, 1832 (Platyhelminthes: Monogenea) from cichlids from Zambezi and Limpopo river basins in Zimbabwe and South Africa: evidence for unexplored species richness.

    Science.gov (United States)

    Zahradníčková, Petra; Barson, Maxwell; Luus-Powell, Wilmien J; Přikrylová, Iva

    2016-09-01

    New findings on Gyrodactylus spp. parasitising African cichlids in southern Africa are presented, comprising data from Zimbabwe and South Africa. Morphometry of opisthaptoral hard parts in combination with nuclear ribosomal DNA sequences confirmed the presence of six species of Gyrodactylus von Nordmann, 1832. Three new species are described from fishes in Zimbabwe: Gyrodactylus chitandiri n. sp. from the gill arches of Coptodon rendalli (Boulenger) and Pseudocrenilabrus philander (Weber); Gyrodactylus occupatus n. sp. from the fins of Oreochromis niloticus (L.), Pharyngochromis acuticeps (Steindachner) and P. philander; and Gyrodactylus parisellei n. sp. from the fins of O. niloticus, P. philander and Tilapia sp. Gyrodactylus nyanzae Paperna, 1973 was also identified from the gills of O. niloticus and C. rendalli collected from two localities in Zimbabwe; these findings represent new host and locality records for this parasite. Gyrodactylus sturmbaueri Vanhove, Snoeks, Volckaert & Huyse, 2011 was identified from P. philander collected in South Africa and Zimbabwe thereby providing new host and locality records for this parasite. Finally, Gyrodactylus yacatli García-Vásquez, Hansen, Christison, Bron & Shinn, 2011 was collected from the fins of O. niloticus and P. philander studied in Zimbabwe; this represents the first record of this species from the continent of Africa. Notably, this study improves upon the knowledge of Gyrodactylus spp. parasitising cichlids from these southern African regions. All species studied were recorded from at least two different cichlid host species indicating trend for a wide range of Gyrodactylus hosts in Africa. Accordingly, this supports the idea of intensive host switching in the course of their evolution. PMID:27522367

  7. Evolutionary History of Lake Tanganyika’s Predatory Deepwater Cichlids

    OpenAIRE

    Kirchberger, Paul C; Sefc, Kristina M; Christian Sturmbauer; Stephan Koblmüller

    2012-01-01

    Hybridization among littoral cichlid species in Lake Tanganyika was inferred in several molecular phylogenetic studies. The phenomenon is generally attributed to the lake level-induced shoreline and habitat changes. These allow for allopatric divergence of geographically fragmented populations alternating with locally restricted secondary contact and introgression between incompletely isolated taxa. In contrast, the deepwater habitat is characterized by weak geographic structure and a high po...

  8. Direct Radiative Effect of Mineral Dust on the Development of African Easterly Waves in Late Summer, 2003-07

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Po-Lun; Zhang, Kai; Shi, Jainn Jong; Matsui, Toshihisa; Arking, Albert

    2012-12-19

    Episodic events of both Saharan dust outbreaks and African easterly waves (AEWs) are observed to move westward over the eastern tropical Atlantic Ocean. The relationship between the warm, dry, and dusty Saharan air layer on the nearby storms has been the subject of considerable debate. In this study, the Weather Research and Forecasting model is used to investigate the radiative effect of dust on the development of AEWs during August and September, the months of maximumtropical cyclone activity, in years 2003–07. The simulations show that dust radiative forcing enhances the convective instability of the environment. As a result, mostAEWsintensify in the presence of a dust layer. The Lorenz energy cycle analysis reveals that the dust radiative forcing enhances the condensational heating, which elevates the zonal and eddy available potential energy. In turn, available potential energy is effectively converted to eddy kinetic energy, in which local convective overturning plays the primary role. The magnitude of the intensification effect depends on the initial environmental conditions, including moisture, baroclinity, and the depth of the boundary layer. The authors conclude that dust radiative forcing, albeit small, serves as a catalyst to promote local convection that facilitates AEW development.

  9. Duration of memory of dominance relationships in a group living cichlid

    Science.gov (United States)

    Hotta, Takashi; Takeyama, Tomohiro; Jordan, Lyndon Alexander; Kohda, Masanori

    2014-09-01

    Animal contests are costly and tend to escalate when rivals have similar competitive abilities. Individuals that remember dominance relationships with rivals may avoid repeated agonistic interactions and hence avoid the costs of repeated escalation of contests. However, it can be difficult to experimentally disentangle the effects of memory from those of loser effects (losers behaving subordinately due to prior defeats). Here, we test whether loser effects or individual memory mediate contest behaviour in the African cichlid, Julidochromis transcriptus. We find that on days 3 and 5 after initial contests, losers display subordinate behaviour to contest winners but not to novel contestants. However, this effect disappears after 7 days, at which time losers do not display subordinate behaviour to either rival. These results show that (1) this fish can recall a previously dominant contestant for up to 5 days and (2) as no subordinate displays were shown to the novel contestant, there are no evidences for loser effects in this species. Such short-term memory of past interactions may have broad significance in social species with repeated interactions.

  10. Proceedings of the Second All African IRPA Regional Radiation Protection Congress

    International Nuclear Information System (INIS)

    The publication has been set up as proceedings of the radiation protection conference. the conference consistes of Radiation Protection Infrastructure and training; the Environmental; Occupational; Medical; Transport and Waste Safety; Emergency and Security; Non Ionizing Radiation and Miscellaneous. This conference consistes of 310p., figs., tabs., refrs

  11. Evolution of opercle shape in cichlid fishes from Lake Tanganyika - adaptive trait interactions in extant and extinct species flocks.

    Science.gov (United States)

    Wilson, Laura A B; Colombo, Marco; Sánchez-Villagra, Marcelo R; Salzburger, Walter

    2015-01-01

    Phenotype-environment correlations and the evolution of trait interactions in adaptive radiations have been widely studied to gain insight into the dynamics underpinning rapid species diversification. In this study we explore the phenotype-environment correlation and evolution of operculum shape in cichlid fishes using an outline-based geometric morphometric approach combined with stable isotope indicators of macrohabitat and trophic niche. We then apply our method to a sample of extinct saurichthyid fishes, a highly diverse and near globally distributed group of actinopterygians occurring throughout the Triassic, to assess the utility of extant data to inform our understanding of ecomorphological evolution in extinct species flocks. A series of comparative methods were used to analyze shape data for 54 extant species of cichlids (N = 416), and 6 extinct species of saurichthyids (N = 44). Results provide evidence for a relationship between operculum shape and feeding ecology, a concentration in shape evolution towards present along with evidence for convergence in form, and significant correlation between the major axes of shape change and measures of gut length and body elongation. The operculum is one of few features that can be compared in extant and extinct groups, enabling reconstruction of phenotype-environment interactions and modes of evolutionary diversification in deep time. PMID:26584885

  12. Evolution of brain-body allometry in Lake Tanganyika cichlids.

    Science.gov (United States)

    Tsuboi, Masahito; Kotrschal, Alexander; Hayward, Alexander; Buechel, Severine Denise; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas

    2016-07-01

    Brain size is strongly associated with body size in all vertebrates. This relationship has been hypothesized to be an important constraint on adaptive brain size evolution. The essential assumption behind this idea is that static (i.e., within species) brain-body allometry has low ability to evolve. However, recent studies have reported mixed support for this view. Here, we examine brain-body static allometry in Lake Tanganyika cichlids using a phylogenetic comparative framework. We found considerable variation in the static allometric intercept, which explained the majority of variation in absolute and relative brain size. In contrast, the slope of the brain-body static allometry had relatively low variation, which explained less variation in absolute and relative brain size compared to the intercept and body size. Further examination of the tempo and mode of evolution of static allometric parameters confirmed these observations. Moreover, the estimated evolutionary parameters indicate that the limited observed variation in the static allometric slope could be a result of strong stabilizing selection. Overall, our findings suggest that the brain-body static allometric slope may represent an evolutionary constraint in Lake Tanganyika cichlids. PMID:27241216

  13. Evolutionary History of Lake Tanganyika’s Predatory Deepwater Cichlids

    Directory of Open Access Journals (Sweden)

    Paul C. Kirchberger

    2012-01-01

    Full Text Available Hybridization among littoral cichlid species in Lake Tanganyika was inferred in several molecular phylogenetic studies. The phenomenon is generally attributed to the lake level-induced shoreline and habitat changes. These allow for allopatric divergence of geographically fragmented populations alternating with locally restricted secondary contact and introgression between incompletely isolated taxa. In contrast, the deepwater habitat is characterized by weak geographic structure and a high potential for gene flow, which may explain the lower species richness of deepwater than littoral lineages. For the same reason, divergent deepwater lineages should have evolved strong intrinsic reproductive isolation already in the incipient stages of diversification, and, consequently, hybridization among established lineages should have been less frequent than in littoral lineages. We test this hypothesis in the endemic Lake Tanganyika deepwater cichlid tribe Bathybatini by comparing phylogenetic trees of Hemibates and Bathybates species obtained with nuclear multilocus AFLP data with a phylogeny based on mitochondrial sequences. Consistent with our hypothesis, largely congruent tree topologies and negative tests for introgression provided no evidence for introgressive hybridization between the deepwater taxa. Together, the nuclear and mitochondrial data established a well-supported phylogeny and suggested ecological segregation during speciation.

  14. Significant impacts of radiation physics in the Weather Research and Forecasting model on the precipitation and dynamics of the West African Monsoon

    Science.gov (United States)

    Li, R.; Jin, J.; Wang, S.-Y.; Gillies, R. R.

    2015-03-01

    Precipitation from the West African Monsoon (WAM) provides food security and supports the economy in the region. As a consequence of the intrinsic complexities of the WAM's evolution, accurate simulations of the WAM and its precipitation regime, through the application of regional climate models, are challenging. We used the coupled Weather Research and Forecasting (WRF) and Community Land Model (CLM) to explore impacts of radiation physics on the precipitation and dynamics of the WAM. Our results indicate that the radiation physics schemes not only produce biases in radiation fluxes impacting radiative forcing, but more importantly, result in large bias in precipitation of the WAM. Furthermore, the different radiation schemes led to variations in the meridional gradient of surface temperature between the north that is the Sahara desert and the south Guinean coastline. Climate diagnostics indicated that the changes in the meridional gradient of surface temperature affect the position and strength of the African Easterly Jet as well as the low-level monsoonal inflow from the Gulf of Guinea. The net result was that each radiation scheme produced differences in the WAM precipitation regime both spatially and in intensity. Such considerable variances in the WAM precipitation regime and dynamics, resulting from radiation representations, likely have strong feedbacks within the climate system and so have inferences when it comes to aspects of predicted climate change both for the region and globally.

  15. Evolutionary history of the Lake Tanganyika cichlid tribe Lamprologini (Teleostei: Perciformes) derived from mitochondrial and nuclear DNA data

    OpenAIRE

    Sturmbauer, Christian; Salzburger, Walter; Duftner, Nina; Schelly, Robert; Koblmüller, Stephan

    2010-01-01

    Lake Tanganyika comprises a cichlid species flock with substrate-breeding and mouthbrooding lineages. While sexual selection via mate choice on male mating color is thought to boost speciation rates in mouthbrooding cichlids, this is not the case in substrate-breeding lamprologines, which mostly form stable pairs and lack sexual dichromatism. We present a comprehensive reconstruction of the evolution of the cichlid tribe Lamprologini, based upon mtDNA sequences and multilocus nuclear DNA (AFL...

  16. Replicated evolution of trophic specializations in an endemic cichlid fish lineage from Lake Tanganyika

    OpenAIRE

    Rüber, Lukas; Verheyen, Erik; Meyer, Axel

    1999-01-01

    The current phylogenetic hypothesis for the endemic Lake Tanganyika cichlid fishes of the tribe Eretmodini is based solely on morphology and suggests that more complex trophic morphologies derived only once from a less specialized ancestral condition. A molecular phylogeny of eretmodine cichlids based on partial mitochondrial DNA cytochrome b and control-region sequences was used to reconstruct the evolutionary sequence of trophic adaptations and to test alternative models of morphological di...

  17. Mesoscale Modeling of Smoke Particles Distribution and Their Radiative Feedback over Northern Sub-Saharan African Region

    Science.gov (United States)

    Yue, Y.; Wang, J.; Ichoku, C. M.; Ellison, L.

    2015-12-01

    Stretching from southern boundary of Sahara to the equator and expanding west to east from Atlantic Ocean coasts to the India Ocean coasts, the northern sub-Saharan African (NSSA) region has been subject to intense biomass burning. Comprised of savanna, shrub, tropical forest and a number of agricultural crops, the extensive fires burn belt covers central and south of NSSA during dry season (from October to March) contributes to one of the highest biomass burning rate per km2 in the world. Due to smoke particles' absorption effects of solar radiation, they can modify the surface and atmosphere temperature and thus change atmospheric stability, height of the boundary layer, regional atmospheric circulation, evaporation rate, cloud formation, and precipitation. Hence, smoke particles emitted from biomass burning over NSSA region has a significant influence to the air quality, weather and climate variability. In this study, the first version of this Fire Energetics and Emissions Research (FEER.v1) emissions of several smoke constituents including light-absorbing organic carbon (OC) and black carbon (BC) are applied to a state-of-science meteorology-chemistry model as NOAA Weather Research and Forecasting Model with Chemistry (WRF-Chem). We analyzed WRF-Chem simulations of surface and vertical distribution of various pollutants and their direct radiative effects in conjunction with satellite observation data from Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar data with Orthogonal Polarization (CALIPSO) to strengthen the importance of combining space measured emission products like FEER.v1 emission inventory with mesoscale model over intense biomass burning region, especially in area where ground-based air-quality and radiation-related observations are limited or absent.

  18. Application of the community radiative transfer model to evaluate satellite-based measurements across the African Easterly Jet over Western Africa

    OpenAIRE

    Ernest, Richard D.

    2007-01-01

    The Community Radiative Transfer Model (CRTM) has been used to determine which polar-orbiter satellite channels are best suited to remotely sense in a cloud-free environment the lower-tropospheric temperature and moisture gradients that determine the location and intensity of the African Easterly Jet over West Africa. This study evaluates the capability of five microwave sensors and three infrared sensors, including both conical- and cross-track scanning instruments. Atmospheric profiles ...

  19. Two types of dominant male cichlid fish: behavioral and hormonal characteristics.

    Science.gov (United States)

    Alcazar, Rosa M; Becker, Lisa; Hilliard, Austin T; Kent, Kai R; Fernald, Russell D

    2016-01-01

    Male African cichlid fish, Astatotilapia burtoni, have been classified as dominant or subordinate, each with unique behavioral and endocrine profiles. Here we characterize two distinct subclasses of dominant males based on types of aggressive behavior: (1) males that display escalating levels of aggression and court females while they establish a territory, and (2) males that display a stable level of aggression and delay courting females until they have established a territory. To profile differences in their approach to a challenge, we used an intruder assay. In every case, there was a male-male confrontation between the resident dominant male and the intruder, with the intruder quickly taking a subordinate role. However, we found that dominant males with escalating aggression spent measurably more time attacking subordinates than did dominant males with stable aggression that instead increased their attention toward the females in their tank. There was no difference in the behavior of intruders exposed to either type of dominant male, suggesting that escalating aggression is an intrinsic characteristic of some dominant males and is not elicited by the behavior of their challengers. Male behavior during the first 15 min of establishing a territory predicts their aggressive class. These two types of dominant males also showed distinctive physiological characteristics. After the intruder assay, males with escalating aggression had elevated levels of 11-ketotestosterone (11-KT), testosterone, estradiol, and cortisol, while those with stable aggression did not. These observations show that the same stimulus can elicit different behavioral and endocrine responses among A. burtoni dominant males that characterize them as either escalating or stable aggressive types. Our ability to identify which individuals within a population have escalating levels of aggressive responses versus those which have stable levels of aggressive responses when exposed to the same stimulus

  20. Molecular phylogeny of African bush-shrikes and allies: tracing the biogeographic history of an explosive radiation of corvoid birds.

    Science.gov (United States)

    Fuchs, Jérôme; Irestedt, Martin; Fjeldså, Jon; Couloux, Arnaud; Pasquet, Eric; Bowie, Rauri C K

    2012-07-01

    The Malaconotidea (e.g., butcherbirds, bush-shrikes, batises, vangas) represent an Old World assemblage of corvoid passerines that encompass many different foraging techniques (e.g., typical flycatchers, flycatcher-shrikes, canopy creepers, undergrowth skulkers). At present, relationships among the primary Malaconotidea clades are poorly resolved, a result that could either be attributed to a rapid accumulation of lineages over a short period of time (hard polytomy) or to an insufficient amount of data having been brought to bear on the problem (soft polytomy). Our objective was to resolve the phylogenetic relationships and biogeographic history of the Malaconotidea using DNA sequences gathered from 10 loci with different evolutionary properties. Given the range of substitution rates of molecular markers we sequenced (mitochondrial, sex-linked, autosomal), we also sought to explore the effect of altering the branch-length prior in Bayesian tree estimation analyses. We found that changing the branch-length priors had no major effect on topology, but clearly improved mixing of the chains for some loci. Our phylogenetic analyses clarified the relationships of several genera (e.g., Pityriasis, Machaerirhynchus) and provide for the first time strong support for a sister-group relationship between core platysteirids and core vangids. Our biogeographic reconstruction somewhat unexpectedly suggests that the large African radiation of malaconotids originated after a single over-water dispersal from Australasia around 45-33.7 mya, shedding new light on the origins of the Afrotropical avifauna. PMID:22475817

  1. Time-place learning in the cichlid angelfish, Pterophyllum scalare.

    Science.gov (United States)

    Gómez-Laplaza, Luis M; Morgan, Elfed

    2005-09-30

    The ability of the cichlid angelfish, Pterophyllum scalare, to associate time and place to locate food, provided twice a day in two different places, was tested. Food was delivered daily in one corner of the tank in the morning and in the diagonally opposite corner in the afternoon, for a 3-week period, and the distribution of the fish in the tank was noted prior to and during feeding time. The results indicate that, in a fairly uniform environment and in the absence of external time cues, angelfish can discriminate and associate time and place to obtain a food reward. It is suggested that they do so by means of an endogenous timing mechanism. PMID:16129239

  2. Current status of the South African research program on the radiation preservation of subtropical fruits

    International Nuclear Information System (INIS)

    In July 1976, the Atomic Energy Board (AEB) entered into a Research Agreement with the International Atomic Energy Agency (IAEA). This was done at the invitation of the Agency, as part of its function of coordinating research programs and assisting in broadening the contact of scientific investigators with similar interests. The relevant AEB research project is that involving radiation preservation of subtropical fruits, which forms part of the IAEA's coordinated program on Technological and Economic Feasibility of Food Irradiation. The report describes the results of several season's research carried out at the AEB in conjunction with the Citrus and Subtropical Fruit Research Institute, Nelspruit, on the radiation treatment of subtropical fruits. A commercial feasibility study for mango processing is summarised and plans for pilot-plant operation are described. Equally promising results have been obtained with respect to disease control and delayed senescence in papayas. Disease in litchis was also markedly reduced by irradiation treatment, but work on this fruit is still at an early stage. In the case of avocados, a greatly reduced dose, with a mild heat treatment, produced delayed ripening without significant adverse effects, and results in a shelf-life extention of about six days. The results obtained show that the irradiation of subtropical fruits holds considerable promise in terms of reduced losses, better fruit quality, improved distribution and large-scale exports

  3. THE BACKGROUND RADIATION AND EXPOSURE LEVELS AT VARIOUS SOUTH AFRICAN WEST COAST MILITARY UNITS

    Directory of Open Access Journals (Sweden)

    Jacques Bezuidenhout

    2014-11-01

    Full Text Available The West Coast of South Africa between St Helena Bay to the north and Langebaan Lagoon to the south is characterised by numerous granite protrusions. These outcrops are elements of the underlying Cape Granite Suite, which forms the bedrock of a large part of the Western Cape. Granite contains high levels of natural radionuclides, which results in high levels of natural background radiation in the surrounding area. The impacts of these high levels of radiation exposure on military personal are of concern. There are four military units located in this part of the West Coast, namely SAS Saldanha, 4 Special Forces Regiment, Langebaan Road Air Force Base and the Military Academy. Different sites in and around these military units were selected and soil samples were taken. Laboratory gamma ray measurements were done to determine the levels of natural radioactive nuclides in the soil samples. The radioactive nuclide concentrations were interpolated and then mapped with the help of geographic information systems (also known as geospatial information systems or GIS software. An evaluation of the annual dose rate of military personnel at the units on the West Coast was made and found to range between 0,017 mSv/y and 0,163 mSv/y. These values were mapped and compared to the average global annual dose rate of 0,070 mSv/y. This article reports on an investigation of these results and the overall exposure levels of personnel from the various military units on the West Coast of South Africa.

  4. Rapid phenotypic evolution during incipient speciation in a continental avian radiation

    Science.gov (United States)

    Campagna, Leonardo; Benites, Pilar; Lougheed, Stephen C.; Lijtmaer, Darío A.; Di Giacomo, Adrián S.; Eaton, Muir D.; Tubaro, Pablo L.

    2012-01-01

    Adaptive radiations have helped shape how we view animal speciation, particularly classic examples such as Darwin's finches, Hawaiian fruitflies and African Great Lakes cichlids. These ‘island’ radiations are comparatively recent, making them particularly interesting because the mechanisms that caused diversification are still in motion. Here, we identify a new case of a recent bird radiation within a continentally distributed species group; the capuchino seedeaters comprise 11 Sporophila species originally described on the basis of differences in plumage colour and pattern in adult males. We use molecular data together with analyses of male plumage and vocalizations to understand species limits of the group. We find marked phenotypic variation despite lack of mitochondrial DNA monophyly and few differences in other putatively neutral nuclear markers. This finding is consistent with the group having undergone a recent radiation beginning in the Pleistocene, leaving genetic signatures of incomplete lineage sorting, introgressive hybridization and demographic expansions. We argue that this apparent uncoupling between neutral DNA homogeneity and phenotypic diversity is expected for a recent group within the framework of coalescent theory. Finally, we discuss how the ecology of open habitats in South America during the Pleistocene could have helped promote this unique and ongoing radiation. PMID:22130601

  5. On the origin of Lake Malawi cichlid species: a population genetic analysis of divergence.

    Science.gov (United States)

    Won, Yong-Jin; Sivasundar, Arjun; Wang, Yong; Hey, Jody

    2005-05-01

    The cichlid fishes of Lake Malawi are famously diverse. However, phylogenetic and population genetic studies of their history have been difficult because of the great amount of genetic variation that is shared between species. We apply a recently developed method for fitting the "isolation with migration" divergence model to a data set of specially designed compound loci to develop portraits of cichlid species divergence. Outgroup sequences from a cichlid from Lake Tanganyika permit model parameter estimates in units of years and effective population sizes. Estimated speciation times range from 1,000 to 17,000 years for species in the genus Tropheops. These exceptionally recent dates suggest that Malawi cichlids as a group experience a very active and dynamic diversification process. Current effective population size estimates range form 2,000 to near 40,000, and to >120,000 for estimates of ancestral population sizes. It appears that very recent speciation and gene flow are among the reasons why it has been difficult to discern the phylogenetic history of Malawi cichlids. PMID:15851665

  6. Impact of increased ultraviolet-B radiation stress due to stratospheric ozone depletion on N2 fixation in traditional African commercial legumes

    International Nuclear Information System (INIS)

    Reports of diminished nodule formation and nitroge-nase activity in some Asian tropical legumes exposed to above-ambient levels of ultraviolet-B (UV-B: 280-315nm) radiation have raised concerns as to the impact of stratospheric ozone depletion on generally poorly developed traditional African farming systems confronted by the high cost and limited availability of chemical fertilisers. These rely on N2-fixing legumes as the cheapest source of N for maintaining soil fertility and sustainable yields in the intrinsically infertile and heterogeneous African soils. In view of this, we examined the effects of supplemental UV-B radiation approximating 15% and 25% depletions in the total ozone column on N2 fixation in eight traditional African commercial legume species representing crop, forest, medicinal, ornamental and pasture categories. In all categories examined, except medicinal, supplemental UV-B had no effect on root non-structural carbohydrates, antho-cyanins and flavonoids, known to signal Rhizobiaceae micro-symbionts and promote nodule formation, or on nodule mass, activity and quantities of N fixed in different plant organs and whole plants. In contrast, in the medicinal category Cyclopia maculata (Honeybush) a slow growing commercially important herbal beverage with naturally high flavonoid concentrations, displayed decreased nodule activity and quantities of N fixed in different plant organs and whole plants with increased UV-B. This study's findings conclude negligible impacts of ozone depletion on nitrogen fixation and soil fertility in most traditional African farming systems, these limited to occasional inhibition of nodule induction in some crops. (author)

  7. A complex mode of aggressive mimicry in a scale-eating cichlid fish.

    Science.gov (United States)

    Boileau, Nicolas; Cortesi, Fabio; Egger, Bernd; Muschick, Moritz; Indermaur, Adrian; Theis, Anya; Büscher, Heinz H; Salzburger, Walter

    2015-09-01

    Aggressive mimicry is an adaptive tactic of parasitic or predatory species that closely resemble inoffensive models in order to increase fitness via predatory gains. Although similarity of distantly related species is often intuitively implicated with mimicry, the exact mechanisms and evolutionary causes remain elusive in many cases. Here, we report a complex aggressive mimicry strategy in Plecodus straeleni, a scale-eating cichlid fish from Lake Tanganyika, which imitates two other cichlid species. Employing targeted sequencing on ingested scales, we show that P. straeleni does not preferentially parasitize its models but—contrary to prevailing assumptions—targets a variety of co-occurring dissimilar looking fish species. Combined with tests for visual resemblance and visual modelling from a prey perspective, our results suggest that complex interactions among different cichlid species are involved in this mimicry system. PMID:26399975

  8. Biological Diversity and Resilience: Lessons from the Recovery of Cichlid Species in Lake Victoria

    Directory of Open Access Journals (Sweden)

    Alex O. Awiti

    2011-03-01

    Full Text Available A fundamental feature of the Anthropocene is the inexorable erosion of the self-repairing capacity or adaptive renewal of natural systems because of natural perturbation, exploitation, or management failure. The concept of resilience offers a systematic framework for understanding the dynamics and variables that govern response dynamics of ecosystems. Resilience of haplochromine cichlids is assessed using limnological and biodiversity changes in Lake Victoria, the world's second largest freshwater lake, over the last five decades. The review explores the resurgence of the haplochromine cichlids using Holling's adaptive renewal cycle and attempts to illustrate how resilience-based management approaches might learn from an inadvertent management experiment. The introduction in the 1980s of the Nile perch (Lates niloticus, a fecund and voracious predator of the endemic phytoplankton feeding haplochromine cichlids, anthropogenic eutrophication, and deep water hypoxia have combined in a synergistic way to increase the vulnerability of the lake ecosystem to perturbations that were hitherto absorbed. However, the upsurge in commercial Nile perch fishing appears to be enabling the resurgence of the haplochromine cichlids. The resurgence of haplochromine cichlids is characterized by phenotypic plasticity, ecological and life history traits and demonstrates the critical role of response diversity in the maintenance of systems resilience. Resilience of the haplochromine cichlids resides in the requisite functional response diversity and habitat diversity that provide the resources for renewal and regeneration. This paper concludes that management of Nile perch fisheries and control of nutrient loading into Lake Victoria could halt or reverse eutrophication, hence offer the best promise for a diverse, productive, and resilient social-ecological system.

  9. Mutational changes of intraspecific agressiveness in the convict cichlid (Cichlasoma nigrofasciatum Guenther) after irradiation of parental spermatogonia and oogonia with different doses of X-rays

    International Nuclear Information System (INIS)

    The agonistic behavior of mated convict cichlids (Cichlasoma nigrofasciatum) derived from gonial germ cells which were exposed to 0 (controls), 250, 500, 1,000, or 2,000 R of X-rays was determined by counting the attacks delivered to subadult conspecifics during the first eight days after spawning. While no day effects and no interactions with sex and radiation dose were found, males were significantly more aggressive in the treatment groups than the corresponding females. The highest aggressivness appeared in F1 pairs derived from parental gonia irradiated with 250 R, and the lowest aggressiveness occurred in the 500-F1 group. These two treatment groups differed significantly from each other, whereas no further significant differences could be detected. F1 males derived from gonial X-irradiation with 750 R could not be mated successfully because they killed their own females. The changes of male aggressiveness reflect reversely the previously published results of changes in social cohesiveness of the individual cichlid fish. (author)

  10. Parasitic infections in ornamental cichlid fish in the Peruvian Amazon.

    Science.gov (United States)

    Aguinaga, Jefferson Yunis; Marcusso, Paulo Fernandes; Claudiano, Gustavo da Silva; Lima, Bruno Tadeu Marotta; Marotta, Bruno L; Sebastião, Fernanda de Alexandre; Fernandes, João Batista Kochenborger; de Moraes, Flávio Ruas; de Moraes, Julieta Rodini Engracia

    2015-01-01

    The aim of this study was to evaluate the prevalence and seasonal distribution of the main parasite species in Amazonian ornamental cichlids that affect their trade. The study was conducted from August 2007 to September 2009. We sampled 3042 specimens from 9 different species, of which 9.47% had at least one type of external parasite. 81.25% of the cases occurred in the dry season. Crenicichla anthurus (28.57%) was the most parasitized, followed by Aequidens diadema (26.32%), Pterophyllum scalare (22.69%), Cichlasoma sp. (9.52%), Apistogramma sp. (3.88%) and Symphysodon aequifasciatus (3.66%). Monogenea was the most abundant group of parasites, occurring in 66.67% of the cases, of which 96.88% occurred in the dry season. This parasite infested 95.68% of Pterophyllum scalare, 76.67% of Apistogramma sp, 33.33% of Cichlasoma sp. and 23.81% of Symphysodon aequifasciatus cases. Ichthyophthirius multifiliis infested 100% of Aequidens diadema, 76.19% of Symphysodon aequifasciatus, 66.67% of Cichlasoma sp, 41.67% of Crenicichla anthurus and 23.33% of Apistogramma sp cases. Myxosporidia infested 58.33% of Crenicichla anthurus. Trichodina infested 4.32% of Pterophyllum scalare. The prevalence of these parasites is related to the season, preferred habitat, fish behavior, individual susceptibility and handling of animals during transportation by fishermen. PMID:25909258

  11. Hydrodynamic drag constrains head enlargement for mouthbrooding in cichlids.

    Science.gov (United States)

    Van Wassenbergh, Sam; Potes, Nuno Zavattieri; Adriaens, Dominique

    2015-08-01

    Presumably as an adaptation for mouthbrooding, many cichlid fish species have evolved a prominent sexual dimorphism in the adult head. Since the head of fishes serves as a bow during locomotion, an evolutionary increase in head volume to brood more eggs can trade-off with the hydrodynamic efficiency of swimming. Here, the differences between males and females in three-dimensional shape and size of the external head surfaces and the effect thereof on drag force during locomotion was analysed for the Nile tilapia (Oreochromis niloticus), a maternal mouthbrooder. To do so, three-dimensional body surface reconstructions from laser scans and computational fluid dynamics simulations were performed. After scaling the scanned specimens to post-cranial body volume, in order to theoretically equalize propulsive power, the external volume of the head of females was 27% larger than that of males (head length + 14%; head width + 9%). These differences resulted in an approximate 15% increase in drag force. Yet, hydrodynamics imposed important constraints on the adaptation for mouthbrooding as a much more drastic drop in swimming efficiency seems avoided by mainly enlarging the head along the swimming direction. PMID:26224567

  12. Alternative Reproductive Tactics in the Shell-Brooding Lake Tanganyika Cichlid Neolamprologus brevis

    Directory of Open Access Journals (Sweden)

    Kazutaka Ota

    2012-01-01

    Full Text Available Alternative reproductive tactics (ARTs are found in several Lake Tanganyika shell-brooding cichlids. Field studies were conducted in the Wonzye population to examine reproductive ecology and ARTs in the Lake Tanganyika shell-brooding cichlid Neolamprologus brevis. We discovered that this fish occurred in both rocky- and sandy-bottom habitats, but in rocky habitats, brood-caring females exclusively occurred in shell-patches that another cichlid species created. All N. brevis of both sexes in the patches were sexually mature, whereas immature males and females with unripe eggs were found frequently in sandy-bottom habitats. Males in sandy-bottom habitats were smaller, but fed more frequently and were in better somatic condition than males in the patches. Similar tendency was found in females. This indicates that N. brevis uses different habitats depending on the stage of its life history, with migration from sandy-bottom habitats to the shell-patches for reproduction. Males in the patches exhibited different behavior patterns: floating above the patches and lying in the patches. The former was larger, more aggressive, and invested less in gonads (relative to body size than the latter. These results accord with those of other shell-brooding Lake Tanganyika cichlids with ARTs, and they therefore suggest the presence of ARTs in N. brevis.

  13. Fitness correlates of male coloration in a Lake Victoria cichlid fish

    NARCIS (Netherlands)

    Maan, Martine E.; van der Spoel, Michael; Jimenez, Paloma Quesada; van Alphen, Jacques J. M.; Seehausen, Ole

    2006-01-01

    Sexual selection by female choice has contributed to the rapid evolution of phenotypic diversity in the cichlid fish species flocks of East Africa. Yet, very little is known about the ecological mechanisms that drive the evolution of female mating preferences. We studied fitness correlates of male n

  14. Divergent mating preferences and nuptial coloration in sibling species of cichlid fish

    NARCIS (Netherlands)

    Sluijs, Inke van der

    2008-01-01

    Mate choice by female cichlid fish from Lake Victoria plays an important role in speciation and the maintenance of species. Females are expected to select against males that are intermediate in their phenotype during the process of speciation driven by sexual selection. To test this, we hybridized t

  15. Parasite-mediated sexual selection and species divergence in Lake Victoria cichlid fish

    NARCIS (Netherlands)

    Maan, Martine E.; Van Rooijen, Anne M. C.; Van Alphen, Jacques J. M.; Seehausen, Ole

    2008-01-01

    We investigate the role of parasite-mediated sexual selection in the divergence of two species of Lake Victoria cichlids. Pundamilia pundamilia and Pundamilia nyererei represent a common pattern of male nuptial colour divergence between haplochromine sister species: metallic grey-blue in P. pundamil

  16. Heritability and heterochrony of polychromatism in a Lake Victoria cichlid fish : Stepping stones for speciation?

    NARCIS (Netherlands)

    Maan, ME; Haesler, MP; Seehausen, O; Van Alphen, JJM

    2006-01-01

    In many haplochromine cichlid fish, male nuptial coloration is subject to female mate choice and plays a central role in the evolution of reproductive isolation between incipient species. Intraspecific variation in male coloration may serve as a target for diversifying sexual selection and provide a

  17. Sexual conflict over breeding substrate causes female expulsion and offspring loss in a cichlid fish

    NARCIS (Netherlands)

    Maan, Martine E.; Taborsky, Michael

    2008-01-01

    Females of the Lake Tanganyika cichlid Lamprologus callipterus exclusively breed in empty snail shells that males collect in their territories. Male-male competition for shells is severe, leading to frequent shell stealing and territory takeover. As a consequence, males have breeding females in thei

  18. Somatostatin and Somatostatin Receptor Gene Expression in Dominant and Subordinate Males of an African Cichlid Fish

    OpenAIRE

    Trainor, Brian C.; Hofmann, Hans A.

    2007-01-01

    Somatostatin is a neuropeptide best known for its inhibitory effects on growth hormone secretion and has recently been implicated in the control of social behavior. Several somatostatin receptor subtypes have been identified in vertebrates, but the functional basis for this diversity is still unclear. Here we investigate the expression levels of the somatostatin prepropeptide and two of its receptors, sstR2, and sstR3, in the brains of socially dominant and subordinate A. burtoni males using ...

  19. The Role of microRNAs in the Repeated Parallel Diversification of Lineages of Midas Cichlid Fish from Nicaragua.

    Science.gov (United States)

    Franchini, Paolo; Xiong, Peiwen; Fruciano, Carmelo; Meyer, Axel

    2016-01-01

    Cichlid fishes are an ideal model system for studying biological diversification because they provide textbook examples of rapid speciation. To date, there has been little focus on the role of gene regulation during cichlid speciation. However, in recent years, gene regulation has been recognized as a powerful force linking diversification in gene function to speciation. Here, we investigated the potential role of miRNA regulation in the diversification of six cichlid species of the Midas cichlid lineage (Amphilophus spp.) inhabiting the Nicaraguan crater lakes. Using several genomic resources, we inferred 236 Midas miRNA genes that were used to predict the miRNA target sites on 8,232 Midas 3'-UTRs. Using population genomic calculations of SNP diversity, we found the miRNA genes to be more conserved than protein coding genes. In contrast to what has been observed in other cichlid fish, but similar to what has been typically found in other groups, we observed genomic signatures of purifying selection on the miRNA targets by comparing these sites with the less conserved nontarget portion of the 3'-UTRs. However, in one species pair that has putatively speciated sympatrically in crater Lake Apoyo, we recovered a different pattern of relaxed purifying selection and high genetic divergence at miRNA targets. Our results suggest that sequence evolution at miRNA binding sites could be a critical genomic mechanism contributing to the rapid phenotypic evolution of Midas cichlids. PMID:27189980

  20. Benefiting Africans

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZHIPING

    2011-01-01

    Along with thriving Sino-African economic and trade ties,Chinese companies have attached greater importance to their social responsibility to Africans.More than 2,000 sweaters woven by Chinese mothers were sent to orphans and disabled children in Kenya and four other African countries in September.This activity was launched by Hengyuanxiang,a leading Chinese wool manufacturer.

  1. Benefiting Africans

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Along with thriving Sino-African economic and trade ties,Chinese companies have attached greater importance to their social responsibility to Africans.More than 2,000 sweaters woven by Chinese mothers were sent to orphans and disabled children in Kenya and four other African countries in September. This activity was launched by Hengyuanxiang,aleading Chinese wool manufacturer.

  2. Nuclear and mitochondrial data reveal different evolutionary processes in the Lake Tanganyika cichlid genus Tropheus

    Directory of Open Access Journals (Sweden)

    Sturmbauer Christian

    2007-08-01

    Full Text Available Abstract Background Cichlid fishes are notorious for their wealth of intra- and interspecific colour pattern diversity. In Lake Tanganyika, the endemic genus Tropheus represents the most impressive example for geographic variation in the pattern and hue of integument colouration, but the taxonomy of the over 100 mostly allopatric colour morphs remains to a large degree unresolved. Previous studies of mitochondrial DNA sequence data revealed polyphyly of the six nominally described species and complex phylogeographic patterns influenced by lake level fluctuations and population admixture, and suggested the parallel evolution of similar colour patterns in divergent evolutionary lineages. A gene tree of a rapidly radiating group may be subject to incomplete and stochastic lineage sorting, and to overcome this problem we used multi-locus, nuclear AFLP data in comparison with mtDNA sequences to study diversification, migration and introgression in Tropheus colour morphs in Lake Tanganyika. Results Significant incongruence between phylogenetic reconstructions from mitochondrial and AFLP data suggested incomplete sorting of mitochondrial haplotypes as well as frequent introgression between differentiated lineages. In contrast to the mitochondrial phylogeny, the AFLP phenogram was largely congruent with species classifications, colour pattern similarities, and in many cases also with the current geographic distribution of populations, and did not produce evidence of convergent colour pattern evolution. Homoplasy in the AFLP data was used to identify populations that were strongly affected by introgression. Conclusion Different evolutionary processes were distinguished by the combination of mitochondrial and AFLP data. Mitochondrial phylogeographic patterns retained signals of large-scale migration events triggered by historical, major lake level fluctuations, whereas AFLP data indicated genetic cohesion among local groups of populations resulting from

  3. Sensitivity of mesoscale modeling of smoke direct radiative effect to the emission inventory: a case study in northern sub-Saharan African region

    International Nuclear Information System (INIS)

    An ensemble approach is used to examine the sensitivity of smoke loading and smoke direct radiative effect in the atmosphere to uncertainties in smoke emission estimates. Seven different fire emission inventories are applied independently to WRF-Chem model (v3.5) with the same model configuration (excluding dust and other emission sources) over the northern sub-Saharan African (NSSA) biomass-burning region. Results for November and February 2010 are analyzed, respectively representing the start and end of the biomass burning season in the study region. For February 2010, estimates of total smoke emission vary by a factor of 12, but only differences by factors of 7 or less are found in the simulated regional (15°W–42°E, 13°S–17°N) and monthly averages of column PM2.5 loading, surface PM2.5 concentration, aerosol optical depth (AOD), smoke radiative forcing at the top-of-atmosphere and at the surface, and air temperature at 2 m and at 700 hPa. The smaller differences in these simulated variables may reflect the atmospheric diffusion and deposition effects to dampen the large difference in smoke emissions that are highly concentrated in areas much smaller than the regional domain of the study. Indeed, at the local scale, large differences (up to a factor of 33) persist in simulated smoke-related variables and radiative effects including semi-direct effect. Similar results are also found for November 2010, despite differences in meteorology and fire activity. Hence, biomass burning emission uncertainties have a large influence on the reliability of model simulations of atmospheric aerosol loading, transport, and radiative impacts, and this influence is largest at local and hourly-to-daily scales. Accurate quantification of smoke effects on regional climate and air quality requires further reduction of emission uncertainties, particularly for regions of high fire concentrations such as NSSA. (paper)

  4. Sensitivity of Mesoscale Modeling of Smoke Direct Radiative Effect to the Emission Inventory: a Case Study in Northern Sub-Saharan African Region

    Science.gov (United States)

    Zhang, Feng; Wang, Jun; Ichoku, Charles; Hyer, Edward J.; Yang, Zhifeng; Ge, Cui; Su, Shenjian; Zhang, Xiaoyang; Kondragunta, Shobha; Kaiser, Johannes W.; Wiedinmyer, Christine; da Silva, Arlindo

    2014-01-01

    An ensemble approach is used to examine the sensitivity of smoke loading and smoke direct radiative effect in the atmosphere to uncertainties in smoke emission estimates. Seven different fire emission inventories are applied independently to WRF-Chem model (v3.5) with the same model configuration (excluding dust and other emission sources) over the northern sub-Saharan African (NSSA) biomass-burning region. Results for November and February 2010 are analyzed, respectively representing the start and end of the biomass burning season in the study region. For February 2010, estimates of total smoke emission vary by a factor of 12, but only differences by factors of 7 or less are found in the simulated regional (15degW-42degE, 13degS-17degN) and monthly averages of column PM(sub 2.5) loading, surface PM(sub 2.5) concentration, aerosol optical depth (AOD), smoke radiative forcing at the top-of-atmosphere and at the surface, and air temperature at 2 m and at 700 hPa. The smaller differences in these simulated variables may reflect the atmospheric diffusion and deposition effects to dampen the large difference in smoke emissions that are highly concentrated in areas much smaller than the regional domain of the study. Indeed, at the local scale, large differences (up to a factor of 33) persist in simulated smoke-related variables and radiative effects including semi-direct effect. Similar results are also found for November 2010, despite differences in meteorology and fire activity. Hence, biomass burning emission uncertainties have a large influence on the reliability of model simulations of atmospheric aerosol loading, transport, and radiative impacts, and this influence is largest at local and hourly-to-daily scales. Accurate quantification of smoke effects on regional climate and air quality requires further reduction of emission uncertainties, particularly for regions of high fire concentrations such as NSSA.

  5. Monogamy in the maternally mouthbrooding Lake Tanganyika cichlid fish Tropheus moorii

    OpenAIRE

    Egger, Bernd; Obermüller, Beate; Phiri, Harris; Sturmbauer, Christian; Sefc, Kristina M

    2006-01-01

    Supported by evidence for assortative mating and polygynandry, sexual selection through mate choice was suggested as the main force driving the evolution of colour diversity of haplochromine cichlids in Lakes Malawi and Victoria. The phylogenetically closely related tribe Tropheini of Lake Tanganyika includes the genus Tropheus, which comprises over 100 colour variants currently classified into six morphologically similar, polyphyletic species. To assess the potential for sexual selection in ...

  6. Phenotypic integration of brain size and head morphology in Lake Tanganyika Cichlids

    OpenAIRE

    Tsuboi, Masahito; González-Voyer, Alejandro; Kolm, N.

    2014-01-01

    Abstract Background Phenotypic integration among different anatomical parts of the head is a common phenomenon across vertebrates. Interestingly, despite centuries of research into the factors that contribute to the existing variation in brain size among vertebrates, little is known about the role of phenotypic integration in brain size diversification. Here we used geometric morphometrics on the morphologically diverse Tanganyikan cichlids to investigate phenotypic integration across key mor...

  7. Laboratory Class Project: Using a Cichlid Fish Display Tank to Teach Students about Complex Behavioral Systems

    OpenAIRE

    Nolan, Brian C.

    2010-01-01

    Laboratory activities serve several important functions in undergraduate science education. For neuroscience majors, an important and sometimes underemphasized tool is the use of behavioral observations to help inform us about the consequences of changes that are occurring on a neuronal level. To help address this concern, the following laboratory exercise is presented. The current project tested the prediction that the most dominant fish in a tank of cichlids will have gained the most benefi...

  8. Color changing and behavioral context in the Amazonian Dwarf Cichlid Apistogramma hippolytae (Perciformes)

    OpenAIRE

    Raoni Rosa Rodrigues; Lucélia Nobre Carvalho; Jansen Zuanon; Kleber Del-Claro

    2009-01-01

    Animal coloration has many functions, and fishes are noted among vertebrates for presenting a wide variety of color patterns. Although in marine fishes the relationship between body coloration and behavioral context is well documented, there's not much information about freshwater fishes. Here we describe color patterns displayed by the dwarf cichlid Apistogramma hippolytae and suggest that these patterns are dependent on different social and behavioral settings. Field observations were condu...

  9. Molecular phylogeny and biogeography of the Neotropical cichlid fish tribe Cichlasomatini (Teleostei: Cichlidae: Cichlasomatinae)

    Czech Academy of Sciences Publication Activity Database

    Musilová, Zuzana; Říčan, Oldřich; Janko, Karel; Novák, J.

    2008-01-01

    Roč. 46, - (2008), s. 659-672. ISSN 1055-7903 R&D Projects: GA MŠk LC06073 Grant ostatní: GA UK(CZ) 182/2004/B-BIO; GA UK(CZ) 139407 Institutional research plan: CEZ:AV0Z50450515 Keywords : molecular phylogeny * Cichlids * south America Subject RIV: EG - Zoology Impact factor: 3.871, year: 2008

  10. On the age and origin of the species flock of haplochromine cichlid fishes of Lake Victoria.

    OpenAIRE

    Fryer, G.

    2001-01-01

    Recent suggestions concerning the age and origin of the flock of haplochromine cichlid fishes in Lake Victoria (East Africa) are considered. These accept as proven the suggestion that Lake Victoria dried out completely in the Late Pleistocene, was dry for several thousand years, and refilled ca. 12400 years ago. Apart from the fact that other geophysical evidence contradicts this claim, its biological implications, which do likewise, have never been considered by those who have accepted it. L...

  11. Monophyletic origin of Lake Victoria cichlid fishes suggested by mitochondrial DNA sequences

    OpenAIRE

    Meyer, Axel; Kocher, Thomas D.; Basasibwaki, Pereti; Wilson, Allan C.

    1990-01-01

    Lake Victoria, together with its satellite lakes, harbours roughly 200 endemic forms of cichlid fishes that are classified as 'haplo-chromines' and yet the lake system is less than a million years old. This 'flock' has attracted attention because of the possibility that it evolved within the lake from one ancestral species and that biologists are thus presented with a case of explosive evolution. Within the past decade, however, morphology has increasingly emphasized the view that the flock m...

  12. Know thine enemy: Intra-sexual selection and sympatric speciation in Lake Victoria cichlid fish

    OpenAIRE

    Dijkstra, Peter Douwe

    2006-01-01

    Speciation by sexual selection research has traditionally concentrated on mechanisms for divergence driven via female mate choice (intersexual selection). The pivotal role of competition between members of the same sex (intrasexual selection) has been largely overlooked. In this thesis, I describe a series of experimental studies investigating the role of intrasexual selection in sympatric divergence, using Lake Victoria haplochromine cichlid fish as a model system. Such experiments are neede...

  13. Sex-specific effects of maternal testosterone on lateralization in a cichlid fish

    OpenAIRE

    Schaafsma, Sara M.; Groothuis, Ton G. G.

    2012-01-01

    Lateralization of cerebral functions is a fundamental aspect of the organization of brain and behaviour in vertebrates. Sex differences in human lateralization have inspired researchers to postulate several hypotheses concerning the effect of prenatal testosterone on lateralization, but few experimental studies have examined these hypotheses. We investigated whether prenatal testosterone affects strength or direction of lateralization in a cichlid fish, Aequidens rivulatus. Eggs were given a ...

  14. Reproductive success and female preference in the amazonian cichlid angel fish, Pterophyllum scalare (Lichtenstein, 1823)

    OpenAIRE

    Maria do Socorro R.F Cacho; Sathyabama Chellappa; Maria Emília Yamamoto

    2006-01-01

    The angel fish, Pterophyllum scalare is a cichlid native to the Amazon Basin of Brazil and is exported as an ornamental fish. In this study the importance of the experience and previous reproductive success of males in mate selection was investigated. In order to investigate reproductive experience, six pairs of males (experienced and inexperienced) and six females were used. Males were placed in an aquarium, where one female was released. Mate selection was verified by the time spent by a fe...

  15. Age, growth, and mortality of the Mayan cichlid (Cichlasoma urophthalmus) from the southeastern Everglades

    OpenAIRE

    Faunce, Craig H.; Patterson, Heather M.; Lorenz, Jerome J.

    2002-01-01

    Mayan cichlids (Cichlasoma urophthalmus) were collected monthly from March 1996 to October 1997 with hook-and-line gear at Taylor River, Florida, an area within the Crocodile Sanctuary of Everglades National Park, where human activities such as fishing are prohibited. Fish were aged by examining thin-sectioned otoliths, and past size-at-age information was generated by using back-calculation techniques. Marginal increment analysis showed that opaque growth zones were annuli deposited between ...

  16. Morphology, molecules, and monogenean parasites: an example of an integrative approach to cichlid biodiversity.

    Directory of Open Access Journals (Sweden)

    Maarten Van Steenberge

    Full Text Available The unparalleled biodiversity of Lake Tanganyika (Africa has fascinated biologists for over a century; its unique cichlid communities are a preferred model for evolutionary research. Although species delineation is, in most cases, relatively straightforward, higher-order classifications were shown not to agree with monophyletic groups. Here, traditional morphological methods meet their limitations. A typical example are the tropheine cichlids currently belonging to Simochromis and Pseudosimochromis. The affiliations of these widespread and abundant cichlids are poorly understood. Molecular work suggested that genus and species boundaries should be revised. Moreover, previous morphological results indicated that intraspecific variation should be considered to delineate species in Lake Tanganyika cichlids. We review the genera Simochromis and Pseudosimochromis using an integrative approach. Besides a morphometric study and a barcoding approach, monogenean Cichlidogyrus (Platyhelminthes: Ancyrocephalidae gill parasites, often highly species-specific, are used as complementary markers. Six new species are described. Cichlidogyrus raeymaekersi sp. nov., C. muterezii sp. nov. and C. banyankimbonai sp. nov. infect S. diagramma. Cichlidogyrus georgesmertensi sp. nov. was found on S. babaulti and S. pleurospilus, C. franswittei sp. nov. on both S. marginatus and P. curvifrons and C. frankwillemsi sp. nov. only on P. curvifrons. As relatedness between Cichlidogyrus species usually reflects relatedness between hosts, we considered Simochromis monotypic because the three Cichlidogyrus species found on S. diagramma belonged to a different morphotype than those found on the other Simochromis. The transfer of S. babaulti, S. marginatus, S. pleurospilus and S. margaretae to Pseudosimochromis was justified by the similarity of their Cichlidogyrus fauna and the intermediate morphology of S. margaretae. Finally parasite data also supported the synonymy between S

  17. Investigation of Acute Toxicity Diazinon, Deltamethrin, Butachlor and pretilachlor on Zebra Cichlid (Cryptoheros nigrofasciatus

    Directory of Open Access Journals (Sweden)

    Ali Sadeghi

    2014-06-01

    Full Text Available Background: The presence of pesticide due to the huge demand for agricultural purposes is very prevalent in surface waters of Iran. These pesticides could finally accumulate in aquatic ecosystems and have been proved to have toxic effects on aquatic animals. The aim of this study was to assess the acute toxicity of Diazinon, Deltamethrin, Butachlor and Pretilachlor on Zebra Cichlid (Cryptoheros nigrofasciatus. Methods: Fish samples were exposed to different concentrations of Diazinon (60% (0, 2, 4, 8, 16 and 32 ppm, Deltamethrin (2.5% (0, 0.02, 0.04, 0.10, 0.20 and 0.40 ppm, butachlor (60% (0, 2, 4, 8, 16 and 32 ppm and pretilachlor (50% (0, 5, 10, 20, 30 and 40 ppm for 96 h within the 100 L glass aquaria and cumulative mortality of Zebra Cichlid fish was calculated in 24-h interval. Results: The very low LC50 obtained for diazinon (5.06±0.37 ppm, deltamethrin (0.15±0.39 ppm, butachlor (8.93±0.26 ppm and pretilachlor (20.72±0.58 ppm indicated that these are highly toxic chemicals. Conclusion: Our results demonstrate that deltamethrin and pretilachlor had the lowest and highest rate of mortality on the Zebra Cichlid respectively.

  18. Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

    Science.gov (United States)

    López-Fernández, Hernán; Arbour, Jessica; Willis, Stuart; Watkins, Crystal; Honeycutt, Rodney L; Winemiller, Kirk O

    2014-01-01

    Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny. PMID:24603485

  19. A One-Year Study of the Diurnal Cycle of Meteorology, Clouds, and Radiation in the West African Sahel Region

    Energy Technology Data Exchange (ETDEWEB)

    Marquardt-Collow, Allison; Ghate, Virendra P.; Miller, Mark A.; Trabachino, Lynne

    2016-01-09

    The diurnal cycles of meteorological and radiation variables are analyzed during the wet and dry seasons over the Sahel region of West Africa during 2006 using surface data collected by the Atmospheric Radiation Measurement (ARM) program’s Mobile Facility, satellite radiation measurements from the Geostationary Earth Radiation Budget (GERB) instrument aboard Meteosat 8, and reanalysis products from the National Center for Environmental Prediction (NCEP). The meteorological analysis builds upon past studies of the diurnal cycle in the region by incorporating diurnal cycles of lower tropospheric wind profiles, thermodynamic profiles, integrated water vapor and liquid water measurements, and cloud radar measurements of frequency and location. These meteorological measurements are complemented by 3-hour measurements of the diurnal cycles of the TOA and surface shortwave (SW) and longwave (LW) radiative fluxes and cloud radiative effects (CREs), and the atmospheric radiative flux divergence (RFD) and atmospheric CREs. Cirrus cloudiness during the dry season is shown to peak in coverage in the afternoon, while convective clouds during the wet season are shown to peak near dawn and have an afternoon minimum related to the rise of the Lifting Condensation Level into the Saharan Air Layer. The LW and SW RFDs and CREs exhibit diurnal cycles during both seasons, but there is a relatively small difference in the LW cycles during the two seasons (10-30 Wm^(-2) depending on the variable and time of day). Small differences in the TOA CREs during the two seasons are overwhelmed by large differences in the surface SW CREs, which exceed 100 Wm^(-2). A significant surface SW CRE during the wet season combined with a negligible TOA SW CRE produces a diurnal cycle in the atmospheric CRE that is modulated primarily by the SW surface CRE, peaks at midday at ~150 Wm^(-2), and varies widely from day to day.

  20. Stability versus diversity of the dentition during evolutionary radiation in cyprinine fish

    OpenAIRE

    Pasco-Viel, Emmanuel; Yang, Lei; Veran, Monette; Balter, Vincent; Mayden, Richard L.; Laudet, Vincent; Viriot, Laurent

    2014-01-01

    Evolutionary radiations, especially adaptive radiations, have been widely studied but mainly for recent events such as in cichlid fish or Anolis lizards. Here, we investigate the radiation of the subfamily Cyprininae, which includes more than 1300 species and is estimated to have originated from Southeast Asia around 55 Ma. In order to decipher a potential adaptive radiation, within a solid phylogenetic framework, we investigated the trophic apparatus, and especially the pharyngeal dentition,...

  1. Rapid sympatric ecological differentiation of crater lake cichlid fishes within historic times

    Directory of Open Access Journals (Sweden)

    Harrod Chris

    2010-05-01

    Full Text Available Abstract Background After a volcano erupts, a lake may form in the cooled crater and become an isolated aquatic ecosystem. This makes fishes in crater lakes informative for understanding sympatric evolution and ecological diversification in barren environments. From a geological and limnological perspective, such research offers insight about the process of crater lake ecosystem establishment and speciation. In the present study we use genetic and coalescence approaches to infer the colonization history of Midas cichlid fishes (Amphilophus cf. citrinellus that inhabit a very young crater lake in Nicaragua-the ca. 1800 year-old Lake Apoyeque. This lake holds two sympatric, endemic morphs of Midas cichlid: one with large, hypertrophied lips (~20% of the total population and another with thin lips. Here we test the associated ecological, morphological and genetic diversification of these two morphs and their potential to represent incipient speciation. Results Gene coalescence analyses [11 microsatellite loci and mitochondrial DNA (mtDNA sequences] suggest that crater lake Apoyeque was colonized in a single event from the large neighbouring great lake Managua only about 100 years ago. This founding in historic times is also reflected in the extremely low nuclear and mitochondrial genetic diversity in Apoyeque. We found that sympatric adult thin- and thick-lipped fishes occupy distinct ecological trophic niches. Diet, body shape, head width, pharyngeal jaw size and shape and stable isotope values all differ significantly between the two lip-morphs. The eco-morphological features pharyngeal jaw shape, body shape, stomach contents and stable isotopes (δ15N all show a bimodal distribution of traits, which is compatible with the expectations of an initial stage of ecological speciation under disruptive selection. Genetic differentiation between the thin- and thick-lipped population is weak at mtDNA sequence (FST = 0.018 and absent at nuclear

  2. THE EFFECT OF UVB RADIATION ON SERUM VITAMIN D AND IONIZED CALCIUM IN THE AFRICAN SPOONBILL (PLATALEA ALBA).

    Science.gov (United States)

    Woodhouse, Sarah J; Rick, Markus

    2016-06-01

    Metabolic bone disease (MBD) was diagnosed in two chicks produced by a captive breeding colony of African spoonbills (Platalea alba). The birds were housed indoor during the winter breeding season and had no access to natural sunlight. When the index cases occurred, the nesting birds and chicks had a mean 25-hydroxyvitamin D (25-OHD) concentration of 9.9 ± 2.7 nmol/L and a mean ionized calcium (iCa) concentration of 0.98 ± 0.12 mmol/L (winter pretreatment). For comparison purposes, serum was collected the following summer; mean 25-OHD was 20.8 ± 3.9 nmol/L and mean iCa was 1.32 ± 0.05 mmol/L (summer). During the following breeding season, ultraviolet B (UVB) lighting was provided to the flock, resulting in a mean 25-OHD of 19.0 ± 5.6 nmol/L and mean iCa of 1.23 ± 0.06 mmol/L (winter treatment 1). Both 25-OHD and iCa were significantly higher compared with winter pretreatment, and 25-OHD was not significantly different from summer, indicating that treatment during the winter months succeeded in increasing 25-OHD levels to summer levels. However, winter treatment 1 and summer iCa were significantly different. During the next breeding season (winter treatment 2), the birds were exposed to a light with higher UVB output. The mean 25-OHD of the flock was 16.5 ± 7.2 nmol/L, and the mean iCa increased to 1.34 ± 0.04 mmol/L. Both were comparable to summer values. Healthy chicks were hatched during both breeding seasons, and no further cases of MBD occurred during the course of the study. Provision of a UVB light source to captive African spoonbills maintained indoors during the winter months can increase 25-OHD and iCa to levels equivalent to those seen in the summer months, when birds have unrestricted access to natural sunlight. UVB lighting is recommended for all breeding spoonbills that do not have access to natural sunlight. PMID:27468015

  3. Radiation sterilisation

    International Nuclear Information System (INIS)

    The South African Atomic Energy Board operates an irradiation plant for the sterilisation of pharmaceutical products at Pelindaba. The advantages of this plant are discussed as well as the position radiation processing currently enjoys in industry

  4. Statistical comparison of models for estimating the monthly average daily diffuse radiation at a subtropical African site

    Energy Technology Data Exchange (ETDEWEB)

    Bashahu, M. [University of Burundi, Bujumbura (Burundi). Institute of Applied Pedagogy, Department of Physics and Technology

    2003-07-01

    Nine correlations have been developed in this paper to estimate the monthly average diffuse radiation for Dakar, Senegal. A 16-year period data on the global (H) and diffuse (H{sub d}) radiation, together with data on the bright sunshine hours (N), the fraction of the sky's (Ne/8), the water vapour pressure in the air (e) and the ambient temperature (T) have been used for that purpose. A model inter-comparison based on the MBE, RMSE and t statistical tests has shown that estimates in any of the obtained correlations are not significantly different from their measured counterparts, thus all the nine models are recommended for the aforesaid location. Three of them should be particularly selected for their simplicity, universal applicability and high accuracy. Those are simple linear correlations between K{sub d} and N/N{sub d}, Ne/8 or K{sub t}. Even presenting adequate performance, the remaining correlations are either simple but less accurate, or multiple or nonlinear regressions needing one or two input variables. (author)

  5. Radiation

    International Nuclear Information System (INIS)

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  6. Testing the carotenoid trade-off hypothesis in the polychromatic Midas cichlid, Amphilophus citrinellus.

    Science.gov (United States)

    Lin, Susan M; Nieves-Puigdoller, Katherine; Brown, Alexandria C; McGraw, Kevin J; Clotfelter, Ethan D

    2010-01-01

    Many animals use carotenoid pigments derived from their diet for coloration and immunity. The carotenoid trade-off hypothesis predicts that, under conditions of carotenoid scarcity, individuals may be forced to allocate limited carotenoids to either coloration or immunity. In polychromatic species, the pattern of allocation may differ among individuals. We tested the carotenoid trade-off hypothesis in the Midas cichlid, Amphilophus citrinellus, a species with two ontogenetic color morphs, barred and gold, the latter of which is the result of carotenoid expression. We performed a diet-supplementation experiment in which cichlids of both color morphs were assigned to one of two diet treatments that differed only in carotenoid content (beta-carotene, lutein, and zeaxanthin). We measured integument color using spectrometry, quantified carotenoid concentrations in tissue and plasma, and assessed innate immunity using lysozyme activity and alternative complement pathway assays. In both color morphs, dietary carotenoid supplementation elevated plasma carotenoid circulation but failed to affect skin coloration. Consistent with observable differences in integument coloration, we found that gold fish sequestered more carotenoids in skin tissue than barred fish, but barred fish had higher concentrations of carotenoids in plasma than gold fish. Neither measure of innate immunity differed between gold and barred fish, or as a function of dietary carotenoid supplementation. Lysozyme activity, but not complement activity, was strongly affected by body condition. Our data show that a diet low in carotenoids is sufficient to maintain both coloration and innate immunity in Midas cichlids. Our data also suggest that the developmental transition from the barred to gold morph is not accompanied by a decrease in innate immunity in this species. PMID:20151818

  7. Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

    Directory of Open Access Journals (Sweden)

    Hernán López-Fernández

    Full Text Available Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.

  8. Histochemical localisation of carbonic anhydrase in the inner ear of developing cichlid fish, Oreochromis mossambicus

    Science.gov (United States)

    Beier, M.; Hilbig, R.; Anken, R.

    2008-12-01

    Inner ear otolith growth in terms of mineralisation mainly depends on the enzyme carbonic anhydrase (CAH). CAH is located in specialised, mitochondria-rich macular cells (ionocytes), which are involved in the endolymphatic ion exchange, and the enzyme is responsible for the provision of the pH-value necessary for otolithic calcium carbonate deposition. In the present study, for the first time the localisation of histochemically demonstrated CAH was analysed during the early larval development of a teleost, the cichlid fish Oreochromis mossambicus. CAH-reactivity was observed already in stage 7 animals (onset of otocyst development; staging follows Anken et al. [Anken, R., Kappel, T., Slenzka, K., Rahmann, H. The early morphogenetic development of the cichlid fish, Oreochromis mossambicus (Perciformes, Teleostei). Zool. Anz. 231, 1-10, 1993]). Neuroblasts (from which sensory and supporting cells are derived) proved to be CAH-positive. Already at stage 12 (hatch), CAH-positive regions could be attributed to ionocyte containing regions both in the so-called meshwork and patches area of the macula (i.e., clearly before ionocytes can be identified on ultrastructural level or by employing immunocytochemistry). In contrast to the circumstances observed in mammalian species, sensory hair cells stained negative for CAH in the cichlid. With the onset of stage 16 (finray primordia in dorsal fin, yolk-sac being increasingly absorbed), CAH-reactivity was observed in the vestibular nerve. This indicates the onset of myelinisation and thus commencement of operation. The localisation of CAH in the inner ear of fish (especially the differences in comparison to mammals) is discussed on the basis of its role in otolith calcification. Since the vestibular system is a detector of acceleration and thus gravity, also aspects regarding effects of altered gravity on CAH and hence on the mineralisation of otoliths in an adaptive process are addressed.

  9. Changes in the acoustic environment alter the foraging and sheltering behaviour of the cichlid Amititlania nigrofasciata.

    Science.gov (United States)

    McLaughlin, Kirsty Elizabeth; Kunc, Hansjoerg P

    2015-07-01

    Anthropogenic noise can affect behaviour across a wide range of species in both terrestrial and aquatic environments. However, behaviours might not be affected in isolation. Therefore, a more holistic approach investigating how environmental stressors, such as noise pollution, affect different behaviours in concert is necessary. Using tank-based noise exposure experiments, we tested how changes in the acoustic environment affect the behaviour of the cichlid Amatitlania nigrofasciata. We found that exposure to anthropogenic noise affected a couple of behaviours: an increase in sheltering was accompanied by a decrease in foraging. Our results highlight the multiple negative effects of an environmental stressor on an individual's behaviour. PMID:25937344

  10. Brain structure evolution in a basal vertebrate clade: evidence from phylogenetic comparative analysis of cichlid fishes

    Directory of Open Access Journals (Sweden)

    Kolm Niclas

    2009-09-01

    Full Text Available Abstract Background The vertebrate brain is composed of several interconnected, functionally distinct structures and much debate has surrounded the basic question of how these structures evolve. On the one hand, according to the 'mosaic evolution hypothesis', because of the elevated metabolic cost of brain tissue, selection is expected to target specific structures mediating the cognitive abilities which are being favored. On the other hand, the 'concerted evolution hypothesis' argues that developmental constraints limit such mosaic evolution and instead the size of the entire brain varies in response to selection on any of its constituent parts. To date, analyses of these hypotheses of brain evolution have been limited to mammals and birds; excluding Actinopterygii, the basal and most diverse class of vertebrates. Using a combination of recently developed phylogenetic multivariate allometry analyses and comparative methods that can identify distinct rates of evolution, even in highly correlated traits, we studied brain structure evolution in a highly variable clade of ray-finned fishes; the Tanganyikan cichlids. Results Total brain size explained 86% of the variance in brain structure volume in cichlids, a lower proportion than what has previously been reported for mammals. Brain structures showed variation in pair-wise allometry suggesting some degree of independence in evolutionary changes in size. This result is supported by variation among structures on the strength of their loadings on the principal size axis of the allometric analysis. The rate of evolution analyses generally supported the results of the multivariate allometry analyses, showing variation among several structures in their evolutionary patterns. The olfactory bulbs and hypothalamus were found to evolve faster than other structures while the dorsal medulla presented the slowest evolutionary rate. Conclusion Our results favor a mosaic model of brain evolution, as certain

  11. Not a simple case - A first comprehensive phylogenetic hypothesis for the Midas cichlid complex in Nicaragua (Teleostei: Cichlidae: Amphilophus).

    Science.gov (United States)

    Geiger, Matthias F; McCrary, Jeffrey K; Schliewen, Ulrich K

    2010-09-01

    Nicaraguan Midas cichlids from crater lakes have recently attracted attention as potential model systems for speciation research, but no attempt has been made to comprehensively reconstruct phylogenetic relationships of this highly diverse and recently evolved species complex. We present a first AFLP (2793 loci) and mtDNA based phylogenetic hypothesis including all described and several undescribed species from six crater lakes (Apoyeque, Apoyo, Asososca Leon, Masaya, Tiscapa and Xiloá), the two great Lakes Managua and Nicaragua and the San Juan River. Our analyses demonstrate that the relationships between the Midas cichlid members are complex, and that phylogenetic information from different markers and methods do not always yield congruent results. Nevertheless, monophyly support for crater lake assemblages from Lakes Apoyeque, Apoyo, A. Leon is high as compared to those from L. Xiloá indicating occurrence of sympatric speciation. Further, we demonstrate that a 'three species' concept for the Midas cichlid complex is inapplicable and consequently that an individualized and voucher based approach in speciation research of the Midas cichlid complex is necessary at least as long as there is no comprehensive revision of the species complex available. PMID:20580847

  12. Cancer and African Americans

    Science.gov (United States)

    ... Population Profiles > Black/African American > Cancer Cancer and African Americans African Americans have the highest mortality rate ... 65MB] At a glance – Top Cancer Sites for African Americans (2008-2012) Cancer Incidence Rates per 100, ...

  13. Aggression and welfare in a common aquarium fish, the Midas cichlid.

    Science.gov (United States)

    Oldfield, Ronald G

    2011-01-01

    Many species of fishes are aggressive when placed in small aquaria. Aggression can negatively affect the welfare of those individuals toward whom it is directed. Animals may behave aggressively in order to defend resources such as food, shelter, mates, and offspring. The decision to defend depends on the distribution of resources and on ecological factors such as number of competitors, amount of available space, and amount of habitat complexity. This study tested the effects of these factors on aggression in a common aquarium fish, the Midas cichlid (Amphilophus citrinellus). The study found that time spent behaving aggressively was not associated with small-scale differences in group size or available space. Aggression was significantly lower in a large aquarium with a complex habitat. Aquaria of sizes typically used in the companion animal (pet) hobby did not provide optimal welfare for cichlids housed with aggressive conspecifics. The public should be aware that this and similar species require larger aquaria with complex habitat, which elicit more natural behavior. PMID:21932947

  14. The gut microbial community of Midas cichlid fish in repeatedly evolved limnetic-benthic species pairs.

    Science.gov (United States)

    Franchini, Paolo; Fruciano, Carmelo; Frickey, Tancred; Jones, Julia C; Meyer, Axel

    2014-01-01

    Gut bacterial communities are now known to influence a range of fitness related aspects of organisms. But how different the microbial community is in closely related species, and if these differences can be interpreted as adaptive is still unclear. In this study we compared microbial communities in two sets of closely related sympatric crater lake cichlid fish species pairs that show similar adaptations along the limnetic-benthic axis. The gut microbial community composition differs in the species pair inhabiting the older of two crater lakes. One major difference, relative to other fish, is that in these cichlids that live in hypersaline crater lakes, the microbial community is largely made up of Oceanospirillales (52.28%) which are halotolerant or halophilic bacteria. This analysis opens up further avenues to identify candidate symbiotic or co-evolved bacteria playing a role in adaptation to similar diets and life-styles or even have a role in speciation. Future functional and phylosymbiotic analyses might help to address these issues. PMID:24733403

  15. Handed foraging behavior in scale-eating cichlid fish: its potential role in shaping morphological asymmetry.

    Directory of Open Access Journals (Sweden)

    Hyuk Je Lee

    Full Text Available Scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika display handed (lateralized foraging behavior, where an asymmetric 'left' mouth morph preferentially feeds on the scales of the right side of its victim fish and a 'right' morph bites the scales of the left side. This species has therefore become a textbook example of the astonishing degree of ecological specialization and negative frequency-dependent selection. We investigated the strength of handedness of foraging behavior as well as its interaction with morphological mouth laterality in P. microlepis. In wild-caught adult fish we found that mouth laterality is, as expected, a strong predictor of their preferred attack orientation. Also laboratory-reared juvenile fish exhibited a strong laterality in behavioral preference to feed on scales, even at an early age, although the initial level of mouth asymmetry appeared to be small. This suggests that pronounced mouth asymmetry is not a prerequisite for handed foraging behavior in juvenile scale-eating cichlid fish and might suggest that behavioral preference to attack a particular side of the prey plays a role in facilitating morphological asymmetry of this species.

  16. Lateralized kinematics of predation behavior in a Lake Tanganyika scale-eating cichlid fish.

    Directory of Open Access Journals (Sweden)

    Yuichi Takeuchi

    Full Text Available Behavioral lateralization has been documented in many vertebrates. The scale-eating cichlid fish Perissodus microlepis is well known for exhibiting lateral dimorphism in its mouth morphology and lateralized behavior in robbing scales from prey fish. A previous field study indicated that this mouth asymmetry closely correlates with the side on which prey is attacked, but details of this species' predation behavior have not been previously analyzed because of the rapidity of the movements. Here, we studied scale-eating behavior in cichlids in a tank through high-speed video monitoring and quantitative assessment of behavioral laterality and kinematics. The fish observed showed a clear bias toward striking on one side, which closely correlated with their asymmetric mouth morphologies. Furthermore, the maximum angular velocity and amplitude of body flexion were significantly larger during attacks on the preferred side compared to those on the nonpreferred side, permitting increased predation success. In contrast, no such lateral difference in movement elements was observed in acoustically evoked flexion during the escape response, which is similar to flexion during scale eating and suggests that they share a common motor control pathway. Thus the neuronal circuits controlling body flexion during scale eating may be functionally lateralized upstream of this common motor pathway.

  17. Male mate preference and size-assortative mating in convict cichlids: A role for female aggression?

    Science.gov (United States)

    Bloch, A N; Estela, V J; Leese, J M; Itzkowitz, M

    2016-09-01

    Many monogamous species demonstrate size-assortative mating patterns within natural populations. To better understand the role of intersexual selection in this process, we examined the effect of male preference for female body size in the convict cichlid (Amatitlania siquia). We provided males with a choice between females that differed in size, relative to each other and in relation to the focal male. Based on previous work, we expected males to prefer the largest available female mates across all treatments. Surprisingly, males spent more time near the smaller of two available females, but only when the other female was larger than the male. Additionally, males spent little time with either of two potential female mates when both females were larger than the male. We hypothesized that while males might prefer the largest of available females, female behavior might limit males from acting on this preference. To test this, males were force paired with a smaller or larger female. Pair formation only occurred when the female was smaller than the male, and females that were larger than their male counterparts showed significantly more aggression when compared to smaller females. Together, these data suggest that in the absence of intrasexual competition, male mate preference for large females in convict cichlids might be limited by female aggression. PMID:27444247

  18. On the age and origin of the species flock of haplochromine cichlid fishes of Lake Victoria.

    Science.gov (United States)

    Fryer, G

    2001-06-01

    Recent suggestions concerning the age and origin of the flock of haplochromine cichlid fishes in Lake Victoria (East Africa) are considered. These accept as proven the suggestion that Lake Victoria dried out completely in the Late Pleistocene, was dry for several thousand years, and refilled ca. 12400 years ago. Apart from the fact that other geophysical evidence contradicts this claim, its biological implications, which do likewise, have never been considered by those who have accepted it. Like those of all previous authors who have seized on the presence of the haplochromine flock of perhaps more than 600 species as evidence of extremely rapid evolution since the lake allegedly refilled, the account completely overlooks the fact that any such desiccation must have eliminated not only the haplochromine cichlids but the entire biota of the lake. Nevertheless, its present fauna not only includes the haplochromines but many other endemic organisms that would not be expected, and whose presence and history demand an explanation if the lake did indeed dry out. No such explanation has been offered, nor does such seem possible. The recent interpretation of events is questioned and rejected. PMID:11375102

  19. Assessment of Mercury Bioaccumulation in Zebra Cichlid (Cichlasoma Nigrofasciatum Exposed to Sublethal Concentrations of Permethrin

    Directory of Open Access Journals (Sweden)

    Mahdi Banaee

    2014-12-01

    Full Text Available Background: Aquatic ecosystems are frequently subjected to contamination by toxic heavy metals and pesticides, yet very little is known about the influence of pesticides on bioaccumulation of heavy metals in aquatic organisms. Mercury is a toxic metal with no known biological benefit to organisms. Bioavailability of mercury in aquatic environments depends on biological and non-biological parameters including other pollutants. Therefore, the objectives of this research were to determine the effects of permethrin on bioaccumulation of mercury in zebra cichlid. Methods: Acute toxicity (LC50 of permethrin and mercury chloride was evaluated by estimating mortality in Probit Model in SPSS (version 19.0 IBM. In sub-lethal toxicity, zebra cichlid (Cichlasoma nigrofasciatum was exposed to various concentrations of permethrin (0.0, 0.40, 0.80, 1.20 and 1.60 µg.L-1 combined with 20 µg.L-1 mercury chloride for 15 days. At the end of the experiment, mercury concentrations were measured using ICP-OES-Perkin elmer (optima 7300-DV. Results: 96 h LC50 values of permethrin and mercury for C. nigrofasciatum were calculated to be 17.55 µg.L-1 and 140.38 µg.L-1, respectively. Our results clearly showed that the bioaccumulation of mercury in the specimens increased with increasing concentrations of permethrin to 1.20 and 1.60 µg.L-1. Conclusion: Increasing the concentration of permethrin had synergistic effects on the bioaccumulation of mercury in fish.

  20. Variability of the infrared complex refractive index of African mineral dust: experimental estimation and implications for radiative transfer and satellite remote sensing

    Directory of Open Access Journals (Sweden)

    C. Di Biagio

    2014-04-01

    Full Text Available Experimental estimations of the infrared refractive index of African mineral dust have been retrieved from laboratory measurements of particle transmission spectra in the wavelength range 2.5–25 μm. Five dust samples collected at Banizoumbou (Niger and Tamanrasset (Algeria during dust events originated from different Western Saharan and Sahelian areas have been investigated. The obtained real (n and imaginary (k parts of the refractive index for the different dust cases vary in the range 1.1–2.7 and 0.05–1.0, respectively, and appear to be strongly sensitive to the mineralogical composition of the particles, especially in the 8–12 μm and 17–25 μm spectral intervals. Dust absorption is controlled mainly by clays, and, in minor fraction, by quartz and Ca-rich minerals. Size distribution, and the coarse fraction in particular, plays also a role in determining the refractive index. Significant differences are obtained when comparing our results with existing experimental estimations available in the literature, and with the values of the OPAC (Optical Properties of Aerosols and Clouds database. The different datasets appear comparable in magnitude, with our values of n and k falling in the range of variability of past studies. However, literature data fail in accurately reproducing the spectral signatures of main minerals, in particular clays, and they significantly overestimate the contribution of quartz. We also found that the real and the imaginary parts of the refractive index from part of literature studies do not verify Kramers–Kronig relations, thus resulting theoretically incorrect. The comparison between our results, from Western Africa, and literature data, from different locations in Europe, Africa, and the Caribbean, nonetheless, confirms the expected large variability of the infrared refractive index of dust, thus highlighting the necessity for an extended systematic investigation. Aerosol intensive optical properties

  1. Evolution of a unique predatory feeding apparatus: functional anatomy, development and a genetic locus for jaw laterality in Lake Tanganyika scale-eating cichlids

    OpenAIRE

    Albertson R Craig; Stewart Thomas A

    2010-01-01

    Abstract Background While bilaterality is a defining characteristic of triploblastic animals, several assemblages have managed to break this symmetry in order to exploit the adaptive peaks garnered through the lateralization of behaviour or morphology. One striking example of an evolved asymmetry in vertebrates comes from a group of scale-eating cichlid fishes from Lake Tanganyika. Members of the Perissodini tribe of cichlid fishes have evolved dental and craniofacial asymmetries in order to ...

  2. Assessing the dietary sources of two cichlid species in River Nile sub-branches: Stomach contents, fatty acids and stable isotopes analyses

    Directory of Open Access Journals (Sweden)

    Mohamad S. Abd El-Karim

    2016-06-01

    Full Text Available We assess the importance of four different food sources as dietary components of Oreochromis niloticus and Sarotherodon galilaeus in Nile sub-branches using stomach contents, fatty acids (FA and stable isotopes (SI analyses. Diatoms were the dominant food items, whereas sand and mud constitute a major part of the stomach contents of both cichlids in the northern ElBehery canal. FAs and SI were compared in cichlids and four potential food sources. Carbon isotopes excluded the fresh macrophyte Myriophyllum spicatum and its epiphytes as a potential food source, whereas FA biomarkers indicated that M. spicatum is assimilated in cichlids’ muscles as detrital materials. FA profiles of cichlids’ muscles were highly enriched by live diatom markers whereas decayed diatoms and bacterial markers were partially present. Carbon isotope signatures of cichlids were much close to that of suspended particulate organic matter (SPOM which elucidated that SPOM was the source of diatoms and bacterial detritus incorporated in cichlids muscles. Cichlids were highly enriched with nitrogen signatures which was a result of increased anthropogenic effects and incorporation of bacterial films. SI and FA analyses precisely indicated that live diatoms and bacteria, detrital macrophytes are the main sources of organic matter incorporated in cichlids muscles.

  3. African dance

    OpenAIRE

    Mumberson, Stephen

    2012-01-01

    The RE Open will be shown at the Mall Gallery London and the international section was judged by major practitioners and educators, print dealers and collectors, President of RE and Keeper of the Ashmolean Museum Dr Bren Unwin, John Purcell, Deborah Roslund, Colin Harrison, Dave Ferry, and Mark Hampson. Piece selected "African Dance" print.

  4. Reticulate phylogeny of gastropod-shell-breeding cichlids from Lake Tanganyika – the result of repeated introgressive hybridization

    Directory of Open Access Journals (Sweden)

    Blanc Michel

    2007-01-01

    Full Text Available Abstract Background The tribe Lamprologini is the major substrate breeding lineage of Lake Tanganyika's cichlid species flock. Among several different life history strategies found in lamprologines, the adaptation to live and breed in empty gastropod shells is probably the most peculiar. Although shell-breeding arose several times in the evolutionary history of the lamprologines, all obligatory and most facultative shell-breeders belong to the so called "ossified group", a monophyletic lineage within the lamprologine cichlids. Since their distinctive life style enables these species to live and breed in closest vicinity, we hypothesized that these cichlids might be particularly prone to accidental hybridization, and that introgression might have affected the evolutionary history of this cichlid lineage. Results Our analyses revealed discrepancies between phylogenetic hypotheses based on mitochondrial and nuclear (AFLP data. While the nuclear phylogeny was congruent with morphological, behavioral and ecological characteristics, several species – usually highly specialized shell-breeders – were placed at contradicting positions in the mitochondrial phylogeny. The discordant phylogenies strongly suggest repeated incidents of introgressive hybridization between several distantly related shell-breeding species, which reticulated the phylogeny of this group of cichlids. Long interior branches and high bootstrap support for many interior nodes in the mitochondrial phylogeny argue against a major effect of ancient incomplete lineage sorting on the phylogenetic reconstruction. Moreover, we provide morphological and genetic (mtDNA and microsatellites evidence for ongoing hybridization among distantly related shell-breeders. In these cases, the territorial males of the inferred paternal species are too large to enter the shells of their mate, such that they have to release their sperm over the entrance of the shell to fertilize the eggs. With sperm

  5. Strong assortative mating by diet, color, size, and morphology but limited progress toward sympatric speciation in a classic example: Cameroon crater lake cichlids.

    Science.gov (United States)

    Martin, Christopher H

    2013-07-01

    Models predict that sympatric speciation depends on restrictive parameter ranges, such as sufficiently strong disruptive selection and assortative mating, but compelling examples in nature have rarely been used to test these predictions. I measured the strength of assortative mating within a species complex of Tilapia in Lake Ejagham, Cameroon, a celebrated example of incipient sympatric adaptive radiation. This species complex is in the earliest stages of speciation: morphological and ecological divergence are incomplete, species differ primarily in breeding coloration, and introgression is common. I captured 27 mated pairs in situ and measured the diet, color, size, and morphology of each individual. I found strong assortative mating by color, size, head depth, and dietary source of benthic or pelagic prey along two independent dimensions of assortment. Thus, Ejagham Tilapia showed strong assortative mating most conducive to sympatric speciation. Nonetheless, in contrast to a morphologically bimodal Sarotherodon cichlid species pair in the lake, Ejagham Tilapia show more limited progress toward speciation, likely due to insufficient strength of disruptive selection on morphology estimated in a previous study (γ = 0.16). This supports the predicted dependence of sympatric speciation on strong assortment and strong disruptive selection by examining a potentially stalled example in nature. PMID:23815664

  6. Evolutionary relationships in the sand-dwelling cichlid lineage of lake tanganyika suggest multiple colonization of rocky habitats and convergent origin of biparental mouthbrooding.

    Science.gov (United States)

    Koblmüller, Stephan; Salzburger, Walter; Sturmbauer, Christian

    2004-01-01

    The cichlid species flock of Lake Tanganyika is comprised of seven seeding lineages that evolved in step with changes of the lake environment. One seeding lineage diversified into at least six lineages within a short period of time. Our study focuses on the diversification of one of these lineages, the Ectodini, comprising highly specialized, sand- and rock-dwelling species. They display two distinct breeding styles: maternal and biparental mouthbrooding. By analyzing three mtDNA gene segments in 30 species representing all 13 described genera, we show that the Ectodini rapidly diversified into four clades at the onset of their radiation. The monotypic genus Grammatotria is likely to represent the most ancestral split, followed by the almost contemporary origin of three additional clades, the first comprising the benthic genus Callochromis, the second comprising the benthic genera Asprotilapia, Xenotilapia, Enantiopus, and Microdontochromis, and the third comprising the semi-pelagic genera Ophthalmotilapia, Cardiopharynx, Cyathopharynx, Ectodus, Aulonocranus, Lestradea, and Cunningtonia. Our study confirms the benthic and sand-dwelling life-style as ancestral. Rocky habitats were colonized independently in the Xenotilapia- and Ophthalmotilapia-clade. The Xenotilapia-clade comprises both maternal and biparental mouthbrooders. Their mode of breeding appears to be highly plastic: biparental mouthbrooding either evolved once in the common ancestor of the clade, to be reverted at least three times, or evolved at least five times independently from a maternally mouthbrooding ancestor. Furthermore, the genera Xenotilapia, Microdontochromis, Lestradea, and Ophthalmotilapia appeared paraphyletic in our analyses, suggesting the need of taxonomic revision. PMID:14743316

  7. Gonad development in Midas cichlids and the evolution of sex change in fishes.

    Science.gov (United States)

    Oldfield, Ronald G

    2011-01-01

    Some fishes mature and function as one sex and later transform to the other sex in response to social interactions. Previous evidence suggested that a change in developmental timing may be involved in the evolution of adult sex change in fishes. The most recent support for this idea came from reports that sex in the Midas cichlid, Amphilophus citrinellus, was determined by social conditions experienced at the juvenile stage. Differentiation as a male was reported to be dependent on large body size relative to group-mates, and thought to be mediated through aggressive interactions. Here I demonstrate that socially controlled sex determination does not occur as was originally reported. Previously, I found that sex was not associated with body size in juveniles either in nature or in captivity. Similarly, I found no association between aggressive behavior and sex in juveniles. I later demonstrated that socially controlled sex determination does not typically occur in the Midas cichlid and closely related species and supported an alternative mechanism to explain large body size in adult males. Finally, in the current study I analyze gonad histology of fish from the same population used by the original authors and lay to rest the idea of socially controlled sex determination in this species. Recent observations of socially controlled sex determination in juveniles of species that typically change sex at the adult stage are examples of phenotypic plasticity, not genetic variation. Therefore, juvenile socially controlled sex determination does not support a theory that a change in developmental timing is involved in the evolution of adult sex change in fishes. PMID:21740508

  8. Tucunarella n. Gen. and other dactylogyrids (Monogenoidea) from cichlid fish (Perciformes) from Peruvian Amazonia.

    Science.gov (United States)

    Mendoza-Franco, Edgar F; Scholz, T; Rozkosná, P

    2010-06-01

    During parasitological research on cichlid fish from the tributaries of the Amazon River around Iquitos, Peru, the following gill monogenoidean species were found: Tucunarella cichlae n. gen. and n. sp. from Cichla monoculus Spix and Agassiz; Gussevia alioides Kritsky, Thatcher, and Boeger, 1986 from Heros severus Heckel; Gussevia asota Kritsky, Thatcher, and Boeger, 1989 from Astronotus ocellatus (Agassiz); Gussevia disparoides Kritsky, Thatcher, and Boeger, 1986 from H. severus (all new geographical records) and Cichlasoma amazonarum Kullander (new host record); Gussevia longihaptor (Mizelle and Kritsky, 1969) Kritsky, Thatcher, and Boeger, 1986 and Gussevia undulata Kritsky, Thatcher, and Boeger, 1986 from C. monoculus ; Sciadicleithrum satanopercae Yamada, Takemoto, Bellay, and Pavanelli, 2008 from Satanoperca jurupari Heckel; and Sciadicleithrum variabilum (Mizelle and Kritsky, 1969) Kritsky, Thatcher, and Boeger, 1989 from C. amazonarum (new host and geographical records). Tucunarella n. gen. is proposed to accommodate a new species, Tucunarella cichlae , which is its type and only known species in the genus. The new genus is characterized by, besides a very large body size (about 1.5 mm vs. much less than 1 mm in other ancyrocephaline genera in Amazonia), a thickened tegument, 1 pair of eyes, overlapping gonads (testis dorsal to the germarium), nonarticulated male copulatory organ (MCO) and accessory piece, a coiled (counterclockwise) MCO, a dextral vaginal aperture, a haptor armed with 2 pairs of anchors (each with broad base and subequal roots, which are marginally folded), and dorsal and ventral bars and 14 hooks with protruding blunt thumbs and 2 different shapes (slender vs. slightly expanded shanks). Illustrations and data on morphological and biometric variability of individual species from different hosts are provided. The present data provide evidence of a relatively wide host specificity of gill monogenoideans parasitic in South American cichlids

  9. Acquisition of Lateralized Predation Behavior Associated with Development of Mouth Asymmetry in a Lake Tanganyika Scale-Eating Cichlid Fish

    OpenAIRE

    Yuichi Takeuchi; Michio Hori; Shinya Tada; Yoichi Oda

    2016-01-01

    The scale-eating cichlid Perissodus microlepis with asymmetric mouth is an attractive model of behavioral laterality: each adult tears off scales from prey fishes' left or right flanks according to the direction in which its mouth is skewed. To investigate the development of behavioral laterality and mouth asymmetry, we analyzed stomach contents and lower jaw-bone asymmetry of various-sized P. microlepis (22 ≤ SL

  10. Evidence for genetic monogamy and female-biased dispersal in the biparental mouthbrooding cichlid Eretmodus cyanostictus from Lake Tanganyika

    OpenAIRE

    Taylor, Martin I.; Rico, Ciro; Balshine, Sigal

    2003-01-01

    In this study, we investigate whether apparent social monogamy (where a species forms a pair bond but may participate in copulations outside the pair bond) corresponds with genetic monogamy (where individuals participate only in copulations within a pair bond) in a biparental mouthbrooding cichlid fish, Eretmodus cyanostictus, from Lake Tanganyika, Africa. Our findings suggest that E. cyanostictus is both socially and genetically monogamous and that monogamy may result from limited opportunit...

  11. Nuclear and mitochondrial data reveal different evolutionary processes in the Lake Tanganyika cichlid genus Tropheus

    OpenAIRE

    Sturmbauer Christian; Koblmüller Stephan; Egger Bernd; Sefc Kristina M

    2007-01-01

    Abstract Background Cichlid fishes are notorious for their wealth of intra- and interspecific colour pattern diversity. In Lake Tanganyika, the endemic genus Tropheus represents the most impressive example for geographic variation in the pattern and hue of integument colouration, but the taxonomy of the over 100 mostly allopatric colour morphs remains to a large degree unresolved. Previous studies of mitochondrial DNA sequence data revealed polyphyly of the six nominally described species and...

  12. Dealing with food and eggs in mouthbrooding cichlids: structural and functional trade-offs in fitness related traits.

    Directory of Open Access Journals (Sweden)

    Tim Tkint

    Full Text Available BACKGROUND: As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species. METHODOLOGY/PRINCIPAL FINDINGS: Because cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a "suction feeder" (Haplochromis piceatus and a "biter" (H. fischeri. The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs. CONCLUSIONS/SIGNIFICANCE: Our findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two

  13. Local variation and parallel evolution: morphological and genetic diversity across a species complex of neotropical crater lake cichlid fishes

    OpenAIRE

    Elmer, Kathryn R; Kusche, Henrik; Lehtonen, Topi K; Meyer, Axel

    2010-01-01

    The polychromatic and trophically polymorphic Midas cichlid fish species complex (Amphilophus cf. citrinellus) is an excellent model system for studying the mechanisms of speciation and patterns of phenotypic diversification in allopatry and in sympatry. Here, we first review research to date on the species complex and the geological history of its habitat. We analyse body shape variation from all currently described species in the complex, sampled from six crater lakes (maximally 1.2 23.9 ky...

  14. Phylogeography, colonization and population history of the Midas cichlid species complex (Amphilophus spp.) in the Nicaraguan crater lakes

    OpenAIRE

    Meyer Axel; Barluenga Marta

    2010-01-01

    Abstract Background Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex Amphilophus spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phy...

  15. Comparative cytogenetics of Neotropical cichlid fishes (Nannacara, Ivanacara and Cleithracara) indicates evolutionary reduction of diploid chromosome numbers

    OpenAIRE

    Hodaňová,Lucie; Kalous, Lukáš; Musilová, Zuzana

    2014-01-01

    Abstract A comparative cytogenetic analysis was carried out in five species of a monophyletic clade of neotropical Cichlasomatine cichlids, namely Cleithracara maronii Steindachner, 1881, Ivanacara adoketa (Kullander & Prada-Pedreros, 1993), Nannacara anomala Regan, 1905, N. aureocephalus Allgayer, 1983 and N. taenia Regan, 1912. Karyotypes and other chromosomal characteristics were revealed by CDD banding and mapped onto the phylogenetic hypothesis based on molecular analyses of four genes, ...

  16. Male-male competition and nuptial-colour displacement as a diversifying force in Lake Victoria cichlid fishes.

    OpenAIRE

    Seehausen, Ole; Schluter, Dolph

    2004-01-01

    We propose a new mechanism for diversification of male nuptial-colour patterns in the rapidly speciating cichlid fishes of Lake Victoria. Sympatric closely related species often display nuptial colours at opposite ends of the spectrum with males either blue or yellow to red. Colour polymorphisms within single populations are common too. We propose that competition between males for breeding sites promotes such colour diversification, and thereby speciation. We hypothesize that male aggression...

  17. The building-up of social relationships: behavioural types, social networks and cooperative breeding in a cichlid

    OpenAIRE

    Schürch, Roger; Rothenberger, Susan; Heg, Dik

    2010-01-01

    Consistent individual differences in behavioural types may not only cause variation in life-history decisions, but may also affect the choice of social partners and sociality in general. Here, we tested whether and how behavioural type influences the establishment of social ties using the cooperatively breeding cichlid, Neolamprologus pulcher. In a habitat saturation experiment with individuals pre-tested for behavioural type, we first analysed whether behavioural type affected the likelihood...

  18. Changes in reproductive life-history strategies in response to nest density in a shell-brooding cichlid, Telmatochromis vittatus.

    OpenAIRE

    Ota, Kazutaka; Hori, Michio; Kohda, Masanori

    2012-01-01

    To determine whether the appearance of a reproductively parasitic tactic varies, and how this variation affects territorial males of the Lake Tanganyika cichlid fish Telmatochromis vittatus, we examined the reproductive ecology of territorial males in Mtondwe and compared it with that of a neighboring Wonzye population, where nest density differs from that at Mtondwe. In Wonzye, with high nest density, male tactics change with their body size from a territorial to a non-territorial parasitic ...

  19. The use of multiple sources of social information in contest behavior: testing the social cognitive abilities of a cichlid fish

    OpenAIRE

    Hotta, Takashi; Takeyama, Tomohiro; Heg, Dik; Awata, Satoshi; Jordan, Lyndon A.; Kohda, Masanori

    2015-01-01

    Theory suggests that living in large social groups with dynamic social interactions often favors the evolution of enhanced cognitive abilities. Studies of how animals assess their own contest ability commonly focus on a single cognitive task, and little is known about the diversity or co-occurrence of cognitive abilities in social species. We examined how a highly social cichlid fish Julidochromis transcriptus uses four major cognitive abilities in contest situations; direct experience, winne...

  20. Early learning and speciation: the effects of early experience on sexual and aggressive behaviour in Lake Victoria cichlid fish

    OpenAIRE

    Verzijden, Machteld Nicolette

    2008-01-01

    The great Lakes of East Africa are inhabited by a great number of haplochromine cichlid species, which form a diverse group in both ecology and nuptial coloration. The large number of sympatrically occuriring closely related species has raised questions about the underlying mechanism for reproductive isolation. In this thesis I describe experiments that test for the effects of early experience on their species assortative behaviour in the contexts of mate choice and male territorial interacti...

  1. Obesity and African Americans

    Science.gov (United States)

    ... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... ss6304.pdf [PDF | 3.38MB] HEALTH IMPACT OF OBESITY More than 80 percent of people with type ...

  2. Evolutionary Fate of the Androgen Receptor-Signaling Pathway in Ray-Finned Fishes with a Special Focus on Cichlids.

    Science.gov (United States)

    Lorin, Thibault; Salzburger, Walter; Böhne, Astrid

    2015-11-01

    The emergence of the steroid system is coupled to the evolution of multicellular animals. In vertebrates in particular, the steroid receptor repertoire has been shaped by genome duplications characteristic to this lineage. Here, we investigate for the first time the composition of the androgen receptor-signaling pathway in ray-finned fish genomes by focusing in particular on duplicates that emerged from the teleost-specific whole-genome duplication. We trace lineage- and species-specific duplications and gene losses for the genomic and nongenomic pathway of androgen signaling and subsequently investigate the sequence evolution of these genes. In one particular fish lineage, the cichlids, we find evidence for differing selection pressures acting on teleost-specific whole-genome duplication paralogs at a derived evolutionary stage. We then look into the expression of these duplicated genes in four cichlid species from Lake Tanganyika indicating, once more, rapid changes in expression patterns in closely related fish species. We focus on a particular case, the cichlid specific duplication of the rac1 GTPase, which shows possible signs of a neofunctionalization event. PMID:26333839

  3. Male convict cichlid 11-ketotestosterone levels throughout the reproductive cycle: an exploratory profile study in laboratory and field populations

    Directory of Open Access Journals (Sweden)

    Natalie April van Breukelen

    2015-05-01

    Full Text Available The convict cichlid (Amatitlania nigrofasciata has been extensively examined in relation to many behavioral topics, such as courtship, pair-bonding, bi-parental care, and territoriality. Recently, this model species has been utilized in studies on genetics, endocrinology, and neuroanatomy, with an ultimate goal of connecting behavior with its underlying mechanisms. The goal of this study was two-fold: (1 profile the circulating levels of plasma 11KT in the male convict cichlid at multiple points during the reproductive cycle and (2 generally compare the hormonal profiles of the widely used laboratory populations and those of a free-living population in the streams of Costa Rica. The results of the field experiment showed that male convict cichlids had higher levels of circulating 11KT during courtship and lower during the parental care and non-breeding phases. The profile of the laboratory population was similar to the profile of the free-living individuals, with significantly higher levels of 11KT occurring during courtship than during parental care, though the level of 11KT during non-breeding phase was elevated in the laboratory. The high levels of 11KT during courtship and low levels of 11KT during parental care found in both the field and the laboratory is similar to what has been reported in other species of teleosts, and may suggest an important function of 11KT in the expression of courtship behavior and the subsequent onset of parental behaviors in this model species.

  4. Expression of arginine vasotocin in distinct preoptic regions is associated with dominant and subordinate behaviour in an African cichlid fish

    OpenAIRE

    Greenwood, Anna K.; Wark, Abigail R.; Fernald, Russell D.; Hofmann, Hans A.

    2008-01-01

    Neuropeptides have widespread modulatory effects on behaviour and physiology and are associated with phenotypic transitions in a variety of animals. Arginine vasotocin (AVT) is implicated in mediating alternative male phenotypes in teleost fish, but the direction of the association differs among species, with either higher or lower AVT related to more territorial behaviour in different fishes. To clarify the complex relationship between AVT and alternative phenotype, we evaluated AVT expressi...

  5. Hematological parameters of Iranian cichlid Iranocichla hormuzensis: Coad, 1982 (Perciformes in Mehran River

    Directory of Open Access Journals (Sweden)

    Ehsan Daneshvar

    2012-12-01

    Full Text Available This study describes the hematological parameters in Iranocichla hormuzensis, an Iranian freshwater cichlid important as ornamental and food fish. Forty fish were captured with seine net at Mehran river Hormozgan province, Iran. Blood was used to determine the total counts of red blood cells (RBC and white blood cells (WBC, hematocrit, mean corpuscular volume (MCV, mean corpuscular hemoglobin (MCH, mean corpuscular hemoglobin concentration (MCHC and morphometric data of erythrocytes. The Iranian fish showed lower RBC and WBC values than the other cichlids (Oreochromis niloticus, O. aureus, O. mossambicus, O. hybrid, Cichlasoma dimerus and Cichla monoculus. Hematocrit did not vary among the species, but MCV, MCH and MCHC in I. hormuzensis were higher than those for O. niloticus, O. aureus, O. hybrid, C. dimerus and C. monoculus. These differences may be related to different life habit of fish. This study suggests that I. hormuzensis is well acclimated to the environment being the first report for its hematology. It is also suggested high efficiency in oxygen transportation, and an efficient inflow of oxygen by the gills, indicating the welfare of fish on this environment.Este estudo descreve os parâmetros hematológicos em Iranocichla hormuzensis, ciclídeo iraniano de água doce, importante como peixe ornamental e como de consumo. Quarenta peixes foram capturados com rede no rio Mehran, província de Hormozgan, Irã. O sangue foi usado para determinar as contagens totais de eritrócitos (RBC e leucócitos (WBC, hematócrito, volume corpuscular médio (MCV, hemoglobina corpuscular média (MCH, concentração de hemoglobina corpuscular média (MCHC e dados morfométricos de eritrócitos. O peixe iraniano mostrou valores menores de RBC e WBC do que outros ciclídeos (Oreochromis niloticus, O. aureus, O. mossambicus, O. hybrid, Cichlasoma dimerus e Cichla monoculus. O hematócrito não variou entre as espécies, mas MCV, MCH e MCHC em I

  6. Radiation

    International Nuclear Information System (INIS)

    The basic facts about radiation are explained, along with some simple and natural ways of combating its ill-effects, based on ancient healing wisdom as well as the latest biochemical and technological research. Details are also given of the diet that saved thousands of lives in Nagasaki after the Atomic bomb attack. Special comment is made on the use of radiation for food processing. (U.K.)

  7. Phytogeography of African Commelinaceae

    Directory of Open Access Journals (Sweden)

    R. B. Faden

    1983-12-01

    Full Text Available Africa (including Madagascar has nearly twice as many species of Commelinaceae as any other continent (approximately 270 species, or about 40% of the total in the family. Of the 17 genera which are native, seven (Anthericopsis, Coleotrype, Palisota, Polyspatha, Pseudoparis, Stanfieldiella and  Triceratella are endemic, the highest percentage generic endemism of any continent. Within Africa gcneric diversity is slightly higher in western than in eastern tropical floras. Species richness, however, is greatest in eastern Africa, mainly due to a high diversity of species of Commelina and Aneilema. Africa shares more genera with Asia (nine than with any other continent. Only one African genus, Buforrestia, is neither endemic nor shared with Asia. Its western African/northeastern South American distribution is unique in the family. Besides Buforrestia, only five other genera of Commelinaceae (out of a total of 50 in the family, occur in both the Old and New Worlds. These genera.  Aneilema, Commelina, Floscopa, Murdannia and  Pollia are all very widespread in the Old World, occurring in Australia and Asia in addition to Africa (both continental and Madagascar. Madagascar is relatively poor in species (31. but these include the endemic Madagascan genus Pseudoparis, the sole African species of Rhopalephora, and the largest number of species of the Afro-Malagasy endemic genus Coleotrype. The high rate of generic endemism of Commelinaceae in Africa probably indicates that Africa was one of the ancient centres of diversity for the family. The high species diversity is more likely due to relatively recent radiations by genera pre-adapted to survival in non-forest habitats. The occurrence of only a small number of genera on both sides of the Atlantic suggests that the Commelinaceae have been evolving independently in the eastern and western hemispheres for a long period.

  8. Radiation

    International Nuclear Information System (INIS)

    Exposure to solar and ionizing radiation increases the risk for cancer in humans. Some 5% of solar radiation is within the ultraviolet spectrum and may cause both malignant melanoma and non-melanocytic skin cancer; the latter is regarded as a benign disease and is accordingly not included in our estimation of avoidable cancers. Under the assumption that the rate of occurrence of malignant melanoma of the buttocks of both men and women and of the scalp of women would apply to all parts of the body in people completely unexposed to solar radiation, it was estimated that approximately 95% of all malignant melanomas arising in the Nordic populations around the year 2000 will be due to exposure to natural ultraviolet radiation, equivalent to an annual number of about 4700 cases, with 2100 in men and 2600 in women, or some 4% of all cancers notified. Exposure to ionizing radiation in the Nordic countries occurs at an average effective dose per capita per year of about 3 mSv (Iceland, 1.1 mSv) from natural sources, and about 1 mSv from man-made sources. While the natural sources are primarily radon in indoor air, natural radionuclides in food, cosmic radiation and gamma radiation from soil and building materials, the man-made sources are dominated by the diagnostic and therapeutic use of ionizing radiation. On the basis of measured levels of radon in Nordic dwellings and associated risk estimates for lung cancer derived from well-conducted epidemiological studies, we estimated that about 180 cases of lung cancer (1% of all lung cancer cases) per year could be avoided in the Nordic countries around the year 2000 if indoor exposure to radon were eliminated, and that an additional 720 cases (6%) could be avoided annually if either radon or tobacco smoking were eliminated. Similarly, it was estimated that the exposure of the Nordic populations to natural sources of ionizing radiation other than radon and to medical sources will each give rise to an annual total of 2120

  9. Evolution of feeding specialization in Tanganyikan scale-eating cichlids: a molecular phylogenetic approach

    Directory of Open Access Journals (Sweden)

    Nishida Mutsumi

    2007-10-01

    Full Text Available Abstract Background Cichlid fishes in Lake Tanganyika exhibit remarkable diversity in their feeding habits. Among them, seven species in the genus Perissodus are known for their unique feeding habit of scale eating with specialized feeding morphology and behaviour. Although the origin of the scale-eating habit has long been questioned, its evolutionary process is still unknown. In the present study, we conducted interspecific phylogenetic analyses for all nine known species in the tribe Perissodini (seven Perissodus and two Haplotaxodon species using amplified fragment length polymorphism (AFLP analyses of the nuclear DNA. On the basis of the resultant phylogenetic frameworks, the evolution of their feeding habits was traced using data from analyses of stomach contents, habitat depths, and observations of oral jaw tooth morphology. Results AFLP analyses resolved the phylogenetic relationships of the Perissodini, strongly supporting monophyly for each species. The character reconstruction of feeding ecology based on the AFLP tree suggested that scale eating evolved from general carnivorous feeding to highly specialized scale eating. Furthermore, scale eating is suggested to have evolved in deepwater habitats in the lake. Oral jaw tooth shape was also estimated to have diverged in step with specialization for scale eating. Conclusion The present evolutionary analyses of feeding ecology and morphology based on the obtained phylogenetic tree demonstrate for the first time the evolutionary process leading from generalised to highly specialized scale eating, with diversification in feeding morphology and behaviour among species.

  10. Symmetry perception in bamboo sharks (Chiloscyllium griseum) and Malawi cichlids (Pseudotropheus sp.).

    Science.gov (United States)

    Schluessel, V; Beil, O; Weber, T; Bleckmann, H

    2014-09-01

    Several species have been shown to perceive symmetry as a measure of superior genetic quality, useful for assessing potential mates or mediating other visual activities such as the selection of food sources. The current study assessed whether Pseudotropheus sp. and Chiloscyllium griseum, two fish species from distantly related groups, possess symmetry perception. In alternative two choice experiments, individuals were tested for spontaneous preferences and trained to discriminate between abstract symmetrical and asymmetrical stimulus pairs. Pair discriminations were followed by extensive categorization experiments. Transfer tests elucidated whether bilaterally symmetrical and rotationally symmetrical stimuli could be distinguished. Sharks were also tested for the degree of dissimilarity between two symbols that could still be detected. While sharks showed both a spontaneous preference for symmetry as well as remarkable discrimination abilities by succeeding in all of the presented tasks, cichlids showed no spontaneous preference, had difficulties in discriminating between symbols and performed poorly in the categorization experiments. Sharks distinguished between bilaterally and rotationally symmetrical stimuli and easily differentiated between a four-armed cross (all arms 90° apart) and a cross where one of the arms was only 45° spaced from the one next to it. Performance did not decline when the separation was extended to 70°, but was significantly reduced at an 80° separation. Results indicate that the ability for symmetry perception varies across fish species and individuals, whereby some can detect even subtle differences in this respect. PMID:24794621

  11. Experimental Infection of the Mayan Cichlid Cichlasoma urophthalmus with the Oomycete Aphanomyces invadans.

    Science.gov (United States)

    Aguirre-Ayala, Daniel; Vidal-Martínez, Víctor Manuel

    2015-08-01

    This study aimed to determine the susceptibility of the Mayan cichlid Cichlasoma urophthalmus to infection with the fungus Aphanomyces invadans (also known as epizootic ulcerative syndrome [EUS]). A total of 27 C. urophthalmus were exposed to the original A. Invadans 2006/86/EC strain by intramuscularly injecting the fish with 25,000 zoospores/ml or exposing the fish to a suspension of 25,000 zoospores/ml in 6-L aquaria for 30 days. To assess the infectious capacity of A. invadans, 3 golden barbs (Puntius semifasciolatus) were infected intramuscularly with 200,000 zoospores/ml. A second experiment using 100 C. urophthalmus was performed for 60 days with 50 fish in each treatment group. A polymerase chain reaction (PCR)-based diagnostic method was used; muscle and gills were the target tissues. In the first experiment, none of the exposed C. urophthalmus developed skin lesions related to A. invadans infection. However, PCR analysis revealed that infection had occurred. For the intramuscular treatment, there were significant differences between the controls and the muscle samples (Fisher's exact test; P 0.05). All golden barbs became infected, as indicated by PCR, and developed skin lesions typical of A. invadans infection. We concluded that C. urophthalmus was infected with A. invadans but was an asymptomatic carrier because skin lesions did not develop. In the second experiment, all fish were negative, suggesting that the fish had cleared the infection by the end of the experiment. PMID:25742055

  12. Phylogeographic Diversity of the Lower Central American Cichlid Andinoacara coeruleopunctatus (Cichlidae

    Directory of Open Access Journals (Sweden)

    S. Shawn McCafferty

    2012-01-01

    Full Text Available It is well appreciated that historical and ecological processes are important determinates of freshwater biogeographic assemblages. Phylogeography can potentially lend important insights into the relative contribution of historical processes in biogeography. However, the extent that phylogeography reflects historical patterns of drainage connection may depend in large part on the dispersal capability of the species. Here, we test the hypothesis that due to their relatively greater dispersal capabilities, the neotropical cichlid species Andinoacara coeruleopunctatus will display a phylogeographic pattern that differs from previously described biogeographic assemblages in this important region. Based on an analysis of 318 individuals using mtDNA ATPase 6/8 sequence and restriction fragment length polymorphism data, we found eight distinct clades that are closely associated with biogeographic patterns. The branching patterns among the clades and a Bayesian clock analysis suggest a relatively rapid colonization and diversification among drainages in the emergent Isthmus of Panama followed by the coalescing of some drainages due to historical connections. We also present evidence for extensive cross-cordillera sharing of clades in central Panama and the Canal region. Our results suggest that contemporary phylogeographic patterns and diversification in Lower Central American fishes reflect an interaction of historical drainage connections, dispersal, and demographic processes.

  13. Effect of mate size on maternal reproductive effort in the convict cichlid Amatitlania siquia

    Institute of Scientific and Technical Information of China (English)

    Ashley R. ROBART

    2012-01-01

    The differential allocation hypothesis predicts individuals will increase their reproductive investment when mated to a high quality partner.In many species of fish with biparental care females prefer large males due to the males' greater ability to raise more offspring to independence.I examined the relationship between mate quality,parental care and number of offspring in a natural population of convict cichlids Amatitlania siquia.The frequency of frontal displays by females was positively correlated with male standard length.Additionally,as males increased in length relative to their mate,females increased the frequency of chases towards predators,while males decreased the number of displays towards brood predators.This trade-off in parental effort within a pair due to mate quality is a key prediction of differential allocation.The number of offspring was correlated with male,but not female,standard length.These results support the differential allocation hypothesis in that females offered more parental care to offspring of a larger male,while their mates decreased the amount of care they provided.Additionally,females benefited in terms of number of offspring by pairing with higher quality mates.Increased female investment may provide an incentive to ensure male care and maintain pair bonding,which could lead to greater reproductive success through increased offspring survival [Current Zoology 58 (1):66-72,2012].

  14. Unusual allometry for sexual size dimorphism in a cichlid where males are extremely larger than females

    Indian Academy of Sciences (India)

    Kazutaka Ota; Masanori Kohda; Tetsu Sato

    2010-06-01

    When males are the larger sex, a positive allometric relationship between male and female sizes is often found across populations of a single species (i.e. Rensch’s rule). This pattern is typically explained by a sexual selection pressure on males. Here, we report that the allometric relationship was negative across populations of a shell-brooding cichlid fish Lamprologus callipterus, although males are extremely larger than females. Male L. callipterus collect and defend empty snail shells in each of which a female breeds. We found that, across six populations, male and female sizes are positively correlated with not only sexual and fecundity selection indices, but also with shell sizes. Given their different reproductive behaviours, these correlations mean that males are required to be more powerful, and thus larger, to transport larger shells, while female bodies are reduced to the shell size to enable them to enter the shells. Among the three size selections (sexual selection, fecundity selection and shell size), shell size explained the allometry, suggesting that females are more strongly subject to size selection associated with shell size availability than males. However, the allometry was violated when considering an additional population where size-selection regimes of males differed from that of other populations. Therefore, sexual size allometry will be violated by body size divergence induced by multiple selection regimes.

  15. Reproductive-tactic-specific variation in sperm swimming speeds in a shell-brooding cichlid.

    Science.gov (United States)

    Fitzpatrick, J L; Desjardins, J K; Milligan, N; Montgomerie, R; Balshine, S

    2007-08-01

    Theory predicts that males experiencing elevated levels of sperm competition will invest more in gonads and produce faster-swimming sperm. Although there is ample evidence in support of the first prediction, few studies have examined sperm swimming speed in relation to sperm competition. In this study, we tested these predictions from sperm competition theory by examining sperm characteristics in Telmatochromis vittatus, a small shell-brooding cichlid fish endemic to Lake Tanganyika. Males exhibit four different reproductive tactics: pirate, territorial, satellite, and sneaker. Pirate males temporarily displace all other competing males from a shell nest, whereas sneaker males always release sperm in the presence of territorial and satellite males. Due to the fact that sneakers spawn in the presence of another male, sneakers face the highest levels of sperm competition and pirates the lowest, whereas satellites and territorials experience intermediate levels. In accordance with predictions, sperm from sneakers swam faster than sperm from males adopting the other reproductive tactics, whereas sperm from pirates was slowest. Interestingly, we were unable to detect any variation in sperm tail length among these reproductive tactics. Thus, sperm competition appears to have influenced sperm energetics in this species without having any influence on sperm size. PMID:17460159

  16. Male mate choice scales female ornament allometry in a cichlid fish

    Directory of Open Access Journals (Sweden)

    Kullmann Harald

    2010-10-01

    Full Text Available Abstract Background Studies addressing the adaptive significance of female ornamentation have gained ground recently. However, the expression of female ornaments in relation to body size, known as trait allometry, still remains unexplored. Here, we investigated the allometry of a conspicuous female ornament in Pelvicachromis taeniatus, a biparental cichlid that shows mutual mate choice and ornamentation. Females feature an eye-catching pelvic fin greatly differing from that of males. Results We show that allometry of the female pelvic fin is scaled more positively in comparison to other fins. The pelvic fin exhibits isometry, whereas the other fins (except the caudal fin show negative allometry. The size of the pelvic fin might be exaggerated by male choice because males prefer female stimuli that show a larger extension of the trait. Female pelvic fin size is correlated with individual condition, suggesting that males can assess direct and indirect benefits. Conclusions The absence of positive ornament allometry might be a result of sexual selection constricted by natural selection: fins are related to locomotion and thus may be subject to viability selection. Our study provides evidence that male mate choice might scale the expression of a female sexual ornament, and therefore has implications for the understanding of the relationship of female sexual traits with body size in species with conventional sex-roles.

  17. Can convict Cichlids (Amatitlania siquia socially learn the degree of predation risk associated with novel visual cues in their environment?

    Directory of Open Access Journals (Sweden)

    Patrick M Barks

    Full Text Available For many animals, the ability to distinguish cues indicative of predation risk from cues unrelated to predation risk is not entirely innate, but rather is learned and improved with experience. Two pathways to such learning are possible. First, an animal could initially express antipredator behaviour toward a wide range of cues and subsequently learn which of those cues are non-threatening. Alternatively, it could initially express no antipredator behaviour toward a wide range of cues and subsequently learn which of them are threatening. While the learned recognition of threatening cues may occur either through personal interaction with a cue (asocial learning or through observation of the behaviour of social companions toward a cue (social learning, the learned recognition of non-threatening cues seems to occur exclusively through habituation, a form of asocial learning. Here, we tested whether convict cichlid fish (Amatitlaniasiquia can socially learn to recognize visual cues in their environment as either threatening or non-threatening. We exposed juvenile convict cichlids simultaneously to a novel visual cue and one of three (visual social cues: a social cue indicative of non-risk (the sight of conspecifics that had previously been habituated to the novel cue, a social cue indicative of predation risk (the sight of conspecifics trained to fear the novel cue, or a control treatment with no social cue. The subsequent response of focal fish, when presented with the novel cue alone, was not influenced by the social cue that they had previously witnessed. We therefore did not find evidence that convict cichlids in our study could use social learning to recognize novel visual cues as either threatening or non-threatening. We consider alternative explanations for our findings.

  18. Heart Disease and African Americans

    Science.gov (United States)

    ... Minority Population Profiles > Black/African American > Heart Disease Heart Disease and African Americans Although African American adults are ... were 30 percent more likely to die from heart disease than non-Hispanic whites. African American women are ...

  19. Infant Mortality and African Americans

    Science.gov (United States)

    ... African American > Infant Heath & Mortality Infant Mortality and African Americans African Americans have 2.2 times the infant mortality rate ... birthweight as compared to non-Hispanic white infants. African Americans had almost twice the sudden infant death syndrome ...

  20. Community Genetics Reveal Elevated Levels of Sympatric Gene Flow among Morphologically Similar but Not among Morphologically Dissimilar Species of Lake Victoria Cichlid Fish

    OpenAIRE

    M. Egas; Seehausen, O.; Mrosso, H D J; D. A. Joyce; Konijnendijk, N.

    2011-01-01

    We examined genetic structure among five species of Lake Victoria haplochromine cichlids in four island communities, using a full factorial sampling design that compared genetic differentiation between pairs of species and populations of varying morphological similarity and geographical proximity. We found that allopatric conspecific populations were on average significantly more strongly differentiated than sympatric heterospecific populations of morphologically similar species. Allopatric h...

  1. Disturbance cues in freshwater prey fishes: Does urea function as an ‘early warning cue’in juvenile convict cichlids and rainbow trout?

    Directory of Open Access Journals (Sweden)

    Grant E. BROWN, Christopher D. JACKSON, Patrick H. MALKA,Élisa JACQUES, Marc-Andre COUTURIER

    2012-04-01

    Full Text Available Freshwater vertebrate and invertebrate prey species commonly rely on chemosensory information, including non-injury released disturbance cues, to assess local predation threats. We conducted laboratory studies to (1 determine if urea can function as a disturbance cue in juvenile convict cichlids and rainbow trout and (2 determine if the background level of urea influences the behavioral response to a subsequent pulse of urea (‘background noise’ hypothesis. In the first series of trials, juvenile cichlids and trout were exposed to urea at varying concentrations (0 to 0.5 mg L-1 for cichlids and 0 to 1.0 mg L-1 for trout. Our results suggest that both cichilds and trout exhibited functionally similar responses to urea and conspecific disturbance cues and that increasing the concentration of urea results in an increase intensity of antipredator behaviour. In the second series of trials, we pre-exposed cichlids or trout to intermediate or high concentrations of urea (or a distilled water control and then tested for the response to a second pulse of urea at at intermediate or high concentrations (versus a distilled water control. Our results demonstrate that pre-exposure to urea reduces or eliminates the response to a second pulse of urea, supporting the background noise hypothesis. Together, our results suggest that pulses of urea, released by disturbed or stressed individuals, may function as an early warning signal in freshwater prey species [Current Zoology 58 (2: 250–259 , 2012].

  2. African Americans and Glaucoma

    Science.gov (United States)

    ... Involved News About Us Donate In This Section African Americans and Glaucoma email Send this article to ... glaucoma is the leading cause of blindness in African Americans. Half of those with glaucoma don't ...

  3. Diabetes in African Americans

    OpenAIRE

    Marshall, M.

    2005-01-01

    African Americans have a high risk for type 2 diabetes. Genetic traits, the prevalence of obesity, and insulin resistance all contribute to the risk of diabetes in the African American community. African Americans have a high rate of diabetic complications, because of poor glycaemic control and racial disparities in health care in the USA. African Americans with diabetes may have an atypical presentation that simulates type 1 diabetes, but then their subsequent clinical course is typical of t...

  4. Color changing and behavioral context in the Amazonian Dwarf Cichlid Apistogramma hippolytae (Perciformes

    Directory of Open Access Journals (Sweden)

    Raoni Rosa Rodrigues

    2009-01-01

    Full Text Available Animal coloration has many functions, and fishes are noted among vertebrates for presenting a wide variety of color patterns. Although in marine fishes the relationship between body coloration and behavioral context is well documented, there's not much information about freshwater fishes. Here we describe color patterns displayed by the dwarf cichlid Apistogramma hippolytae and suggest that these patterns are dependent on different social and behavioral settings. Field observations were conducted underwater in a pond in Central Amazonia, Brazil. We recorded six body coloration patterns related to seven different kinds of behavioral activities: foraging, resting, reproductive and agonistic displays, aggression (attacking and fleeing and parental care. Changes in coloration occur rapidly and take only a few seconds. Females on parental care exhibited a unique pattern that are more persistent and probably manifests more slowly. In the shallow and clear waters of the natural environment of this dwarf cichlid, color communication seems to constitute an efficient way to display information about individual mood, social status and reproductive readiness, contributing to minimize loss of energy in unnecessary interactions.Coloração animal tem diferentes funções, e os peixes se destacam entre os vertebrados por apresentarem uma grande diversidade de padrões de cores. Embora se conheça relativamente bem a relação entre coloração e contexto comportamental para peixes marinhos, pouco se sabe para os peixes de água doce. Nós descrevemos os padrões de coloração de um ciclídeo amazônico, Apistogramma hippolytae, e sugerimos como esses padrões são dependentes das características sociais e comportamentais. Realizamos observações subaquáticas utilizando mergulho livre em campo durante o dia em uma lagoa na Amazônia Central. Nós caracterizamos seis padrões de coloração associados a sete comportamentos diferentes: alimentação, repouso

  5. Population structure and reproductive behavior of Sinaloa cichlid Cichlasoma beani (Jordan, 1889 in a tropical reservoir

    Directory of Open Access Journals (Sweden)

    Melgen A. García-Lizárraga

    2011-01-01

    Full Text Available The population structure and reproductive condition of the Sinaloa cichlid Cichlasoma beani from samples obtained from June 2000 to July 2001 were determined. Samples in the first week each month from the largest trader of tilapia in the Aguamilpa Reservoir in Mexico and were caught in gillnets (9.6 and 11.4 cm stretch-mesh size. Of 596 specimens, there were 427 males and 169 females; monthly sex ratio, frequency of lengths by the multinomial distribution, timing of reproduction, condition index, and size at first maturity was determined. Differences in the sex ratio and monthly totals were significant, favoring males, except for September 2000 and March 2001. From one (August 2000 to three modal groups (July 2000 and June 2001 were identified by size. There were no significant differences in standard length weight relationships by sex, which indicated that a shared model for both genders is appropriate, and isometric growth was detected. Based on the proportion of mature and partially matures fish, the main reproductive period was April through June; size at first maturity was 18.9 cm. Water temperature was not significantly related to the percentage of mature and partially matures Sinaloa cichlids or spawning. These findings provide information for regulating the Cichlasoma beani fishery in this region such minimum legal size and non-fishing period.Se determinó la estructura poblacional y condición reproductiva del cíclido de Sinaloa Cichlasoma beani desde junio de 2000 a julio de 2001. Las muestras se obtuvieron de la captura comercial de tilapia en el embalse de Aguamilpa, México durante la primera semana de cada mes. Los especímenes se capturaron con redes de enmalle (9,6 y 11,4 cm de tamaño de malla. De los 596 organismos recolectados, 427 fueron machos y 169 hembras. Se determinó la proporción de sexos mensual, grupos modales de tallas a través de una distribución multinomial, época reproductiva, índice de condición y talla

  6. Protective Effects of Silymarin Extract on Malthion-Induced Zebra Cichlid (Cichlasoma Nigrofasciatum Hepatotoxicity

    Directory of Open Access Journals (Sweden)

    Mahdi Banaee

    2015-03-01

    Full Text Available Background: There is much evidence indicating that natural substances from edible and medicinal plants possess powerful antioxidant and hepatoprotective activities. The objective of the present study was to investigate the potential hepatoprotective effect of silymarin in fish exposed to malathion. Methods: Zebra cichlid fish were allocated into five groups of which one group received normal feed and served as control. Fish from group 2 were treated with 0.1 mg.L-1 malathion. Fish from group 3 and 4 were fed with enriched diet with 1400 mg and 2100 mg silymarin per 1 kg feed, respectively. While fish from group 5 and 6 were fed with enriched diet with 1400 mg and 2100 mg silymarin per 1 kg feed, respectively and simultaneously were treated with 0.1 mg.L-1 malathion for 15 days. Activities of hepatic enzymes including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase were evaluated. Oxidative stress was ascertained by measuring malondialdehyde as marker of lipid peroxidation and total cellular antioxidant capacity. Results: Exposure to malathion caused a significant increase in MDA levels and altered AST, ALT, ALP and LDH activities in liver tissues (p<0.05. The hepatic antioxidant capacity was significantly lowered in malathion treated fish as compared to the control group (p<0.05. Treatment with silymarin significantly ameliorated these changes in the malathion-treated groups. Conclusion: These finding demonstrated that silymarin have protective effects against the toxic influence of malathion on the examined biochemical parameters in liver tissue of fish.

  7. Growth and social behavior in a cichlid fish are affected by social rearing environment and kinship

    Science.gov (United States)

    Hesse, Saskia; Thünken, Timo

    2014-04-01

    Living in groups is a widespread phenomenon in many animal taxa. The reduction of predation risk is thought to be an important cause for the formation of groups. Consequently, grouping behavior is particularly pronounced during vulnerable life stages, i.e., as juveniles. However, group living does not only provide benefits but also imposes costs on group members, e.g., increased competition for food. Thus, benefits of grouping behavior might not be evident when predation risk is absent. The adaptive significance of living and also developing in a group independent from predation risk has received relatively little attention although this might have important implications on the evolution and maintenance of group living. The first aim of the present study was to examine whether the social environment affects juvenile performance in the cichlid fish Pelvicachromis taeniatus and, secondly, whether kinship affects social behavior. Kin selection theory predicts benefits from grouping with kin. Here, we demonstrate that juveniles reared in a group grow on average faster compared to juveniles reared in isolation under standardized laboratory conditions without predation risk. Furthermore, we found significant differences in social behavior between juveniles reared in a group and reared in isolation. Fish reared in isolation were significantly more aggressive and less willing to shoal than group-reared fish. As expected, genetic relatedness influenced social behavior in group-reared fish as well: dyads of juveniles consisting of kin showed increased group cohesiveness compared to non-kin dyads. We discuss the potential benefits of group living in general and living with kin in particular.

  8. A genetic demographic analysis of Lake Malawi rock-dwelling cichlids using spatio-temporal sampling.

    Science.gov (United States)

    Husemann, Martin; Nguyen, Rachel; Ding, Baoqing; Danley, Patrick D

    2015-06-01

    We estimated the effective population sizes (Ne ) and tested for short-term temporal demographic stability of populations of two Lake Malawi cichlids: Maylandia benetos, a micro-endemic, and Maylandia zebra, a widespread species found across the lake. We sampled a total of 351 individuals, genotyped them at 13 microsatellite loci and sequenced their mitochondrial D-loop to estimate genetic diversity, population structure, demographic history and effective population sizes. At the microsatellite loci, genetic diversity was high in all populations. Yet, genetic diversity was relatively low for the sequence data. Microsatellites yielded mean Ne estimates of 481 individuals (±99 SD) for M. benetos and between 597 (±106.3 SD) and 1524 (±483.9 SD) individuals for local populations of M. zebra. The microsatellite data indicated no deviations from mutation-drift equilibrium. Maylandia zebra was further found to be in migration-drift equilibrium. Temporal fluctuations in allele frequencies were limited across the sampling period for both species. Bayesian Skyline analyses suggested a recent expansion of M. zebra populations in line with lake-level fluctuations, whereas the demographic history of M. benetos could only be estimated for the very recent past. Divergence time estimates placed the origin of M. benetos within the last 100 ka after the refilling of the lake and suggested that it split off the sympatric M. zebra population. Overall, our data indicate that micro-endemics and populations in less favourable habitats have smaller Ne , indicating that drift may play an important role driving their divergence. Yet, despite small population sizes, high genetic variation can be maintained. PMID:25891855

  9. The role of otolith size in hearing – Insights from cichlid fishes

    Directory of Open Access Journals (Sweden)

    Tanja Schulz-Mirbach

    2015-10-01

    Full Text Available Otolithic end organs in fishes function as accelerometers and are involved in the senses of balance and hearing (e.g. Popper et al. 2005. Otolith mass and shape are likely decisive factors influencing otolith motion, but while it is largely unknown how different shapes affect otolith movement relative to the sensory epithelium (Popper et al. 2005, greater otolith mass is predicted to result in enhanced stimulation of sensory hair cells and improved hearing (Lychakov and Rebane 2005. What few studies exist on this topic, however, yielded contradicting results in that they did or did not find a correlation between increased otolith mass and enhanced hearing (see Kéver et al. 2014. We investigated the relationship between otolith morphology (including 3D-models of otoliths based on high-resolution microCT imaging and otolith weight and hearing abilities in cichlids while comparing three species (Etroplus maculatus, Hemichromis guttatus, Steatocranus tinanti with different swimbladder morphology and hearing abilities (Schulz-Mirbach et al. 2014. We predicted Etroplus maculatus—the species that displays the best hearing sensitivities—to possess larger/heavier otoliths. As swimbladder extensions in this species are connected to the lagena, we further predicted to find heavier lagenar otoliths. Compared to H. guttatus and S. tinanti, E. maculatus showed the heaviest saccular otoliths, while lagenar otoliths were significantly thinner and lighter than in the former two species, apparently contradicting the hypothesis that the lagena and its otolith are primarily involved in improved hearing abilities. Our results support the idea that there is no ‘simple’ relationship between otolith weight, ancilliary auditory structures and hearing abilities. 3D-models of inner ears and otoliths may be ideally suited for future studies modeling complex otolith motion and thus, may provide a better understanding of how otolith morphology contributes to inner

  10. Mechanism of action of endosulfan as disruptor of gonadal steroidogenesis in the cichlid fish Cichlasoma dimerus.

    Science.gov (United States)

    Da Cuña, Rodrigo H; Rey Vázquez, Graciela; Dorelle, Luciana; Rodríguez, Enrique M; Guimarães Moreira, Renata; Lo Nostro, Fabiana L

    2016-09-01

    The organochlorine pesticide endosulfan (ES) is used in several countries as a wide spectrum insecticide on crops with high commercial value. Due to its high toxicity to non-target animals, its persistence in the environment and its ability to act as an endocrine disrupting compound in fish, ES use is currently banned or restricted in many other countries. Previous studies on the cichlid fish Cichlasoma dimerus have shown that waterborne exposure to ES can lead to both decreased pituitary FSH content and histological alterations of testes. As gonadotropin-stimulated sex steroids release from gonads was inhibited by ES in vitro, the aim of the present study was to elucidate possible mechanisms of disruption of ES on gonadal steroidogenesis in C. dimerus, as well as compare the action of the active ingredient (AI) with that of currently used commercial formulations (CF). Testis and ovary fragments were incubated with ES (AI or CF) and/or steroidogenesis activators or precursors. Testosterone and estradiol levels were measured in the incubation media. By itself, ES did not affect hormone levels. Co-incubation with LH and the adenylate cyclase activator forskolin caused a decrease of the stimulated sex steroids release. When co-incubated with precursors dehydroandrostenedione and 17αhydroxyprogesterone, ES did not affect the increase caused by their addition alone. No differences were observed between the AI and CFs, suggesting that the effect on steroidogenesis disruption is mainly caused by the AI. Results indicate that action of ES takes place downstream of LH-receptor activation and upstream of the studied steroidogenic enzymes. PMID:27235598

  11. Sexual selection on color and behavior within and between cichlid populations: Implications for speciation

    Institute of Scientific and Technical Information of China (English)

    Michael J.PAUERS; Jeffrey S.MCKINNON

    2012-01-01

    Sexual selection is widely viewed as playing a central role in hapiochromine cichlid speciation.Hypothetically,once divergent mate preferences evolve among populations of these fishes,reproductive isolation follows and the populations begin to behave as different species.Various studies have examined patterns of assortative mating among species and sometimes populations,but few have examined variation in directional preferences,especially among populations of the same species.We investigated mate choice behavior in two populations of Labeotropheus fuelleborni,a Lake Malawi endemic.We test whether mating.preferences between populations are based on the same traits and in the same direction as preferences within populations.We examine the potential contributions of two classes of trait,color patterns and behaviors,to reproductive isolation.When females chose between either two males of their own population,or two from another,female preferences were generally similar (for the female population) across the two contexts.Mate choice patterns differed between (female) populations for a measure of color,but only modestly for male behavior.In a separate experiment we simultaneously offered females a male of their own population and a male from a different population.In these trials,females consistently preferred males from their own population,which were also the males that displayed more frequently than their opponents,but not necessarily those with color traits suggested to be most attractive in the previous experiment.Thus directional preferences for chroma and related aspects of color may be important when females are presented with males of otherwise similar phenotypes,but may play little role in mediating assortative mating among populations with substantially different color patterns.A preference for male behavior could play some role in speciation if males preferentially court same-population females,as we have observed for the populations studied herein.

  12. Efficacy of an ototoxic aminoglycoside (gentamicin) on the differentiation of the inner ear of cichlid fish

    Science.gov (United States)

    Schönleber, J.; Anken, R. H.

    2004-01-01

    Previous investigations revealed that the growth of fish inner ear otoliths depends on the amplitude and the direction of gravity, thus suggesting the existence of a (negative) feedback mechanism. In the course of these experiments, it was shown that altered gravity both affected otolith size (and thus the provision of the proteinacious matrix) as well as the incorporation of calcium. It is hitherto unknown, as of whether sensory hair cells are involved either in the regulation of otolith growth or in the provision of otolithic material (such as protein or inorganic components) or even both. The ototoxic aminoglycoside gentamicin (GM) damages hair cells in many vertebrates (and is therefore used for the treatment of Meniere's disease in humans). The present study was thus designed to determine as of whether vestibular sensory cells are needed for otolith growth by applying GM in order to induce a (functionally relevant) loss of these cells. Developing cichlid fish Oreochromis mossambicus were therefore immersed in 120 mg/l GM for 10 or 21 days. At the beginning and at the end of the experimental periods, the fish were incubated in the calcium-tracer alizarin complexone (AC). After the experiment, otoliths were dissected and the area grown during GM-exposure (i.e., the area enclosed by the two AC labellings) was determined planimetrically. The results showed that incubating the animals in a GM-solution had no effect on otolith growth, but the development of otolith asymmetry was affected. Ultrastructural examinations of the sensory hair cells revealed that they had obviously not been affected by GM-treatment (no degenerative morphological features observed). Overall, the present results suggest that hair cells are not affected by GM concerning their possible role in (general) otolith growth, but that these cells indeed might have transitionally been impaired by GM resulting in a decreased capacity of regulating otolith symmetry.

  13. African American Suicide

    Science.gov (United States)

    African American Suicide Fact Sheet Based on 2012 Data (2014) Overview • In 2012, 2,357 African Americans completed suicide in the U.S. Of these, ... 46 per 100,000. • The suicide rate for African Americans ages 10-19 was 2.98 per ...

  14. Temperature and Ca2+-dependence of the sarcoplasmic reticulum Ca2(+)-ATPase in haddock, salmon, rainbow trout and zebra cichlid

    DEFF Research Database (Denmark)

    Godiksen, Helene; Jessen, Flemming

    2002-01-01

    the enzyme or its membrane lipid environment is still a matter of discussion. In this study we compared the temperature dependence and Ca2+-dependence of SR Ca2+-ATPase in haddock (Melanogrammus aeglefinus), salmon (Salmo, salar), rainbow trout (Oncorhynchus mykiss) and zebra cichlid (Cichlasoma...... nigrofasciatum). The Arrhenius plot of zebra cichlid showed a break point at 20 degreesC, and the haddock Arrhenius plot was non-linear with pronounced changes in slope in the. temperature area, 6-14 degreesC. In Arrhenius plot from both salmon and rainbow trout a plateau exists with an almost constant SR Ca2......+- ATPase activity. The temperature range of the plateau was 14-21 and 18-25 degreesC in salmon and rainbow trout, respectively. Ca2+-dependence in the four different fish species investigated was very similar with half maximal activation (K-0.5) between 0.2 and 0.6 muM and half maximal inhibition (I-0...

  15. Induced cytochrome P450 1A activity in cichlid fishes from Guandu River and Jacarepagua Lake, Rio de Janeiro, Brazil

    International Nuclear Information System (INIS)

    The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ('Nile tilapia', Oreochromis niloticus and 'acara', Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepagua Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes. - Increased EROD activity in the liver of cichlid fishes indicated that Guandu River, the source of drinking water supply for Rio de Janeiro is polluted by CYP1A-inducing chemicals

  16. Induced cytochrome P450 1A activity in cichlid fishes from Guandu River and Jacarepagua Lake, Rio de Janeiro, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Parente, Thiago E.M.; Oliveira, Ana C.A.X. de [Laboratorio de Toxicologia Ambiental, Escola Nacional de Saude Publica - FIOCRUZ, Av Brasil 4036, Predio de Expansao do Campus, Rio de Janeiro, RJ 21041-361 (Brazil); Paumgartten, Francisco J.R. [Laboratorio de Toxicologia Ambiental, Escola Nacional de Saude Publica - FIOCRUZ, Av Brasil 4036, Predio de Expansao do Campus, Rio de Janeiro, RJ 21041-361 (Brazil)], E-mail: paum@ensp.fiocruz.br

    2008-03-15

    The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ('Nile tilapia', Oreochromis niloticus and 'acara', Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepagua Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes. - Increased EROD activity in the liver of cichlid fishes indicated that Guandu River, the source of drinking water supply for Rio de Janeiro is polluted by CYP1A-inducing chemicals.

  17. Functional Diversification within a Predatory Species Flock

    OpenAIRE

    Burress, Edward D.; Alejandro Duarte; Serra, Wilson S.; Marcelo Loueiro; Gangloff, Michael M.; Lynn Siefferman

    2013-01-01

    Ecological speciation is well-known from adaptive radiations in cichlid fishes inhabiting lentic ecosystems throughout the African rift valley and Central America. Here, we investigate the ecological and morphological diversification of a recently discovered lotic predatory Neotropical cichlid species flock in subtropical South America. We document morphological and functional diversification using geometric morphometrics, stable C and N isotopes, stomach contents and character evolution. Thi...

  18. Alternative reproductive tactics in snail shell-brooding cichlids diverge in energy reserve allocation.

    Science.gov (United States)

    von Kuerthy, Corinna; Tschirren, Linda; Taborsky, Michael

    2015-05-01

    Life history theory predicts that the amount of resources allocated to reproduction should maximize an individual's lifetime reproductive success. So far, resource allocation in reproduction has been studied mainly in females. Intraspecific variation of endogenous energy storage and utilization patterns of males has received little attention, although these patterns may vary greatly between individuals pursuing alternative reproductive tactics (ARTs). ARTs are characterized by systematic variation of behavioral, physiological, and often morphological traits among same-sex conspecifics. Some individuals may rely on previously accumulated reserves, because of limited foraging opportunities during reproduction. Others may be able to continue foraging during reproduction, thus relying on reserves to a lesser extent. We therefore predicted that, if male tactics involve such divergent limitations and trade-offs within a species, ARTs should correspondingly differ in energy reserve allocation and utilization. To test this prediction, we studied short-term and long-term reserve storage patterns of males in the shell-brooding cichlid Lamprologus callipterus. In this species, bourgeois males investing in territory defense, courtship, and guarding of broods coexist with two distinct parasitic male tactics: (1) opportunistic sneaker males attempting to fertilize eggs by releasing sperm into the shell opening when a female is spawning; and (2) specialized dwarf males attempting to enter the shell past the spawning female to fertilize eggs from inside the shell. Sneaker males differed from other male types by showing the highest amount of accumulated short-term and long-term fat stores, apparently anticipating their upcoming adoption of the nest male status. In contrast, nest males depleted previously accumulated energy reserves with increasing nest holding period, as they invest heavily into costly reproductive behaviors while not taking up any food. This conforms to a capital

  19. African Otter Workshop

    OpenAIRE

    Jan Reed-Smith; Hughes Akpona; Grace Yoxon

    2016-01-01

    All concerned thought this was an excellent workshop with important progress made towards creating a viable beginning of an African Otter Network. There is a long road ahead but the 2015 African Otter Workshop is a start on developing range country partners, activists and researchers as well as collaborating on issue identification and resolution which will assist in preserving at least some refugia for Africa’s otters. A list of actions was agreed on, including the creation of an African Ott...

  20. African and non-African admixture components in African Americans and an African Caribbean population.

    Science.gov (United States)

    Murray, Tanda; Beaty, Terri H; Mathias, Rasika A; Rafaels, Nicholas; Grant, Audrey Virginia; Faruque, Mezbah U; Watson, Harold R; Ruczinski, Ingo; Dunston, Georgia M; Barnes, Kathleen C

    2010-09-01

    Admixture is a potential source of confounding in genetic association studies, so it becomes important to detect and estimate admixture in a sample of unrelated individuals. Populations of African descent in the US and the Caribbean share similar historical backgrounds but the distributions of African admixture may differ. We selected 416 ancestry informative markers (AIMs) to estimate and compare admixture proportions using STRUCTURE in 906 unrelated African Americans (AAs) and 294 Barbadians (ACs) from a study of asthma. This analysis showed AAs on average were 72.5% African, 19.6% European and 8% Asian, while ACs were 77.4% African, 15.9% European, and 6.7% Asian which were significantly different. A principal components analysis based on these AIMs yielded one primary eigenvector that explained 54.04% of the variation and captured a gradient from West African to European admixture. This principal component was highly correlated with African vs. European ancestry as estimated by STRUCTURE (r(2)=0.992, r(2)=0.912, respectively). To investigate other African contributions to African American and Barbadian admixture, we performed PCA on approximately 14,000 (14k) genome-wide SNPs in AAs, ACs, Yorubans, Luhya and Maasai African groups, and estimated genetic distances (F(ST)). We found AAs and ACs were closest genetically (F(ST)=0.008), and both were closer to the Yorubans than the other East African populations. In our sample of individuals of African descent, approximately 400 well-defined AIMs were just as good for detecting substructure as approximately 14,000 random SNPs drawn from a genome-wide panel of markers. PMID:20717976

  1. Dactylogyrids (Monogenea) parasitic on cichlids from northern Brazil, with description of two new species of Sciadicleithrum and new host and geographical records.

    Science.gov (United States)

    Paschoal, Fabiano; Scholz, Tomáš; Tavares-Dias, Marcos; Luque, José L

    2016-01-01

    Two new species of Sciadicleithrum Kritsky, Thatcher and Boeger, 1989 are described from two cichlids from the Araguarí River, State of Amapá, northern Brazil. Sciadicleithrum edgari n. sp. from Satanoperca jurupari (Heckel, 1840) differs from all congeneric species in the morphology (hook-shaped, with middle process and distally bifurcate) of the accessory piece of the male copulatory organ (MCO). Sciadiclethrum araguariensis n. sp. from Crenicichla labrina (Spix and Agassiz, 1831) can be distinguished from all other species by a Y-shaped accessory piece of MCO. In addition to the description of two new species, new host and geographical records of six dactylogyrid monogeneans from cichlid fishes are presented. PMID:26751887

  2. The role of the Yala swamp lakes in conservation of Lake Victoria region haplochromine cichlids: evidence from molecular genetic and trophic ecology studies

    OpenAIRE

    Abila, R.; Salzburger, W; Ndonga, M.F.; Owiti, D.O.; Barluenga, M.

    2006-01-01

    Lake Kanyaboli (Kenya), a satellite lake of Lake Victoria, has been suggested as a potential refugium for haplochromine cichlids that have gone extinct in Lake Victoria. We employed mitochondrial DNA and microsatellite DNA molecular markers as well as feeding ecology studies to re- evaluate the evolutionary and ecological significance of Lake Kanyaboli haplochromines. The mitochondrial DNA and microsatellite markers revealed high genetic diversity in the endangered Xystichromis phytophagus an...

  3. Genetic and morphological population differentiation in the rock-dwelling and specialized shrimp-feeding cichlid fish species Altolamprologus compressiceps from Lake Tanganyika, East Africa

    OpenAIRE

    Spreitzer, Maria Luise; Mautner, Selma; Makasa, Lawrence; Sturmbauer, Christian

    2011-01-01

    With about 250 endemic species, Lake Tanganyika contains an extraordinarily diverse cichlid fish fauna, and thus represents an ideal model system for the study of pathways and processes of speciation. The Lamprologini form the most species-rich tribe in Lake Tanganyika comprising about 100 species in seven genera, most of which are endemic to the lake. They are territorial substrate-breeders and represent a monophyletic tribe. By combined analysis of population genetics and geometric morphome...

  4. Are accessory hearing structures linked to inner ear morphology? Insights from 3D orientation patterns of ciliary bundles in three cichlid species

    OpenAIRE

    Schulz-Mirbach, Tanja; Ladich, Friedrich; Plath, Martin; Metscher, Brian D.; Heß, Martin

    2014-01-01

    Background: Cichlid fishes show considerable diversity in swim bladder morphology. In members of the subfamily Etroplinae, the connection between anterior swim bladder extensions and the inner ears enhances sound transmission and translates into an improved hearing ability. We tested the hypothesis that those swim bladder modifications coincide with differences in inner ear morphology and thus compared Steatocranus tinanti (vestigial swim bladder), Hemichromis guttatus (large swim bladder wit...

  5. Disturbance cues in freshwater prey fishes: Does urea function as an‘early warning cue’in juvenile convict cichlids and rainbow trout?

    Institute of Scientific and Technical Information of China (English)

    Grant E. BROWN; Christopher D. JACKSON; Patrick H. MALKA; (E)lisa JACQUES; Marc-Andre COUTURIER

    2012-01-01

    Freshwater vertebrate and invertebrate prey species commonly rely on chemosensory information,including non-injury released disturbance cues,to assess local predation threats.We conducted laboratory studies to (1) determine if urea can function as a disturbance cue in juvenile convict cichlids and rainbow trout and (2) determine if the background level of urea influences the behavioral response to a subsequent pulse of urea ('background noise' hypothesis).In the first series of trials,juvenile cichlids and trout were exposed to urea at varying concentrations (0 to 0.5 mg L-1 for cichlids and 0 to 1.0 mg L-1 for trout).Our results suggest that both cichilds and trout exhibited functionally similar responses to urea and conspecific disturbance cues and that increasing the concentration of urea results in an increase intensity of antipredator behaviour.In the second series of trials,we pre-exposed cichlids or trout to intermediate or high concentrations of urea (or a distilled water control) and then tested for the response to a second pulse of urea at at intermediate or high concentrations (versus a distilled water control).Our results demonstrate that pre-exposure to urea reduces or eliminates the response to a second pulse of urea,supporting the background noise hypothesis.Together,our results suggest that pulses of urea,released by disturbed or stressed individuals,may function as an early warning signal in freshwater prey species [Current Zoology 58 (2):250-259,2012].

  6. Responses of the Mullet, Liza auratus and the Cichlid, Oreochromis niloticus from Lake Manzala (Egypt) to Heterophyd Infection

    OpenAIRE

    E.A. Hassan; M.F.M. Soliman; M.A. Ghobashy

    2010-01-01

    In this study, the occurrence of heterophyid infection in two well-known hosts of heterophyd in Egyptian lake (Manzala); the mullet, Liza auratus and the cichlid, Oreochromis niloticus was investigated. Furthermore, the potential factors that possibly affect the occurrence of the infection including host sex, length, weight and seasonal variation were considered. The pathological response of the two fish host to the infection was studied. Results showed that the prevalence, abundance and inte...

  7. Physiological and growth responses of two African species, Acacia karroo and Themeda triandra, to combined increases in CO2 and UV-B radiation

    International Nuclear Information System (INIS)

    The interactive effects of increased carbon dioxide (CO2) concentration and ultraviolet-B (UV-B, 280–320 nm) radiation on Acacia karroo Hayne, a C3 tree, and Themeda triandra Forsk., a C4 grass, were investigated. We tested the hypothesis that A. karroo would show greater CO2-induced growth stimulation than T. triandra, which would partially explain current encroachment of A. karroo into C4 grasslands, but that increased UV-B could mitigate this advantage. Seedlings were grown in open-top chambers in a greenhouse in ambient (360 μmol mol-1) and elevated (650 μmol mol-1) CO2, combined with ambient (1.56 to 8.66 kJ m-2 day-1) or increased (2.22 to 11.93 kJ m-2 day-1) biologically effective (weighted) UV-B irradiances. After 30 weeks, elevated CO2 had no effect on biomass of A. karroo, despite increased net CO2 assimilation rates. Interaction between UV-B and CO2 on stomatal conductance was found, with conductances decreasing only where elevated CO2 and UV-B were supplied separately. Increases in water use efficiencies, foliar starch concentrations, root nodule numbers and total nodule mass were measured in elevated CO2. Elevated UV-B caused only an increase in foliar carbon concentrations. In T. triandra, net CO2 assimilation rates were unaffected in elevated CO2, but stomatal conductances and foliar nitrogen concentrations decreased, and water use efficiencies increased. Biomass of all vegetative fractions, particularly leaf sheaths, was increased in elevated CO2. and was accompanied by increased leaf blade lengths and individual leaf and leaf sheath masses. However, tiller numbers were reduced in elevated CO2. Significantly moderating effects of elevated UV-B were apparent only in individual masses of leaf blades and sheaths, and in total sheath and shoot biomass. The direct CO2-induced growth responses of the species therefore do not support the hypothesis of CO2-driven woody encroachment of C4 grasslands. Rather, differential changes in resource use

  8. Keeping African Masks Real

    Science.gov (United States)

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  9. Empowering African States

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China helps bring lasting peace and stability to Africa African think tanks expressed a high opinion of China’s role in helping build African peace and security at the first meeting of the China-Africa Think Tanks Forum. The

  10. African Literature as Celebration.

    Science.gov (United States)

    Achebe, Chinua

    1989-01-01

    Describes the Igbo tradition of "Mbari," a communal creative enterprise that celebrates the world and the life lived in it through art. Contrasts the cooperative, social dimension of pre-colonial African culture with the exclusion and denial of European colonialism, and sees new African literature again celebrating human presence and dignity. (AF)

  11. Ecology and life history of an Amazon floodplain cichlid: the discus fish Symphysodon (Perciformes: Cichlidae

    Directory of Open Access Journals (Sweden)

    William G. R. Crampton

    2008-12-01

    Full Text Available The discus fishes of the genus Symphysodon are popular ornamental cichlids that occur in floodplain lakes and flooded forests of the lowland Amazon Basin. These habitats are characterized by extreme seasonal fluctuations in the availability of food, shelter and dissolved oxygen, and also the densities of predators and parasites. Most aspects of discus biology are influenced by these fluctuating conditions. This paper reports an autoecological study of the western Amazonian discus S. haraldi (until recently classified as S. aequifasciatus. This species feeds predominantly on algal periphyton, fine organic detritus, plant matter, and small aquatic invertebrates. At high water it forages alone or in small groups in flooded forests. At low water it forms large aggregations in fallen tree crowns along lake margins. Breeding occurs at the beginning of the flood season, ensuring that the progeny are well grown before the next low water period. Symphysodon haraldi is an iteroparous partial spawner, reaches reproductive maturity within a year, and undertakes parental care of its eggs and larvae. The timing of spawning events, and/or the rate of brood survival, may be influenced by fluctuations in the flood level, resulting in a non-unimodal distribution of size classes for the subsequent 1+ cohort.Os acarás-disco do gênero Symphysodon são peixes ornamentais comumente encontrados em lagos e florestas alagadas das planícies inundadas da Amazônia. Estes habitats são caracterizados por uma variação sazonal extrema na disponibilidade de alimento, abrigo e oxigênio dissolvido, e também pela densidade de predadores e parasitas. A maioria dos aspectos da biologia do acará-disco são influenciados por esta variabilidade de condições sazonais. Este artigo apresenta um estudo autoecológico de S. haraldi (até recentemente classificado como S. aequifasciatus da Amazônia Ocidental. Os acarás-disco alimentam-se predominantemente de perifiton, detritos

  12. South African Association of Physicists in Medicine and Biology: 26. annual congress

    International Nuclear Information System (INIS)

    The twenty-sixth annual congress of the South African Association of Physicists in Medicine and Biology was held from 18-21 March 1986 in Pretoria. Papers delivered on the conference covered subjects like medical physics, radiotherapy, radiation protection, calibration of radiation monitors, radiation detectors, radiation doses and dosimetry

  13. African Easterly Waves and convective activity in wet and dry sequences of the West African Monsoon

    OpenAIRE

    Lavaysse, Christophe; Diedhiou, Arona; Laurent, Henry; Lebel, Thierry

    2006-01-01

    Janicot and Sultan (Geophys Res Lett 28(3):523-526, 2001) and Sultan et al. (J Clim 16(21):3389-3406, 2003) showed evidence of an intra-seasonal signal of Sahelian rainfall corresponding to wet and dry sequences of the West African Monsoon. Using NCEP/NCAR reanalysis, NOAA outgoing longwave radiation (OLR) and observed daily rainfall over West Africa from 1968 to 1990, this paper investigates the variability of 3 to 5-day African Easterly Waves (AEWs),. convection and their relationship with ...

  14. African Peacekeepers in Africa

    DEFF Research Database (Denmark)

    Emmanuel, Nikolas G.

    2015-01-01

    peacekeeping operations in the region. It is important to add that the international community has frequently tried to facilitate the deployment of African armed forces with aid and training. From this reality, the following study goes beyond the current literature by focusing on the international factors...... behind African participation in United Nations (UN) peacekeeping operations in Africa. In doing so, this research focuses on US military aid and foreign troop training from 2002 to 2012, and its impact on African deployments into UN peacekeeping missions in Africa. As can be expected, such third...

  15. Reading the African context

    OpenAIRE

    Musonda Bwalya

    2012-01-01

    There is so much alienation, pain and suffering in our today�s world. In this vein, African Christianity, a voice amongst many voices, should seek to be a transformational religion for the whole of life, affecting all facets of human life towards a fuller life of all in Africa. This article sought to highlight and point to some of the major societal challenges in the African context which African Christianity, as a life-affirming religion, should continue to embrace, re-embrace and engag...

  16. Capitalism and African business cultures

    OpenAIRE

    Taylor, Scott D.

    2014-01-01

    Scholars and practitioners once commonly linked 'African culture' to a distinctive 'African capitalism', at odds with genuine capitalism and the demands of modern business. Yet contemporary African business cultures reveal that a capitalist ethos has taken hold within both state and society. The success and visibility of an emergent, and celebrated, class of African big business reveals that business and profit are culturally acceptable. Existing theories of African capitalism are ill-equippe...

  17. Reproductive success and female preference in the amazonian cichlid angel fish, Pterophyllum scalare (Lichtenstein, 1823

    Directory of Open Access Journals (Sweden)

    Maria do Socorro R. F. Cacho

    2006-03-01

    Full Text Available The angel fish, Pterophyllum scalare is a cichlid native to the Amazon Basin of Brazil and is exported as an ornamental fish. In this study the importance of the experience and previous reproductive success of males in mate selection was investigated. In order to investigate reproductive experience, six pairs of males (experienced and inexperienced and six females were used. Males were placed in an aquarium, where one female was released. Mate selection was verified by the time spent by a female near one of the males. To evaluate reproductive success, six pairs of males were tested, each pair consisting of a successful male and an unsuccessful one. Again, time spent with one of the males was considered as an indication of preference by the female. Each female was then paired with an unsuccessful male and their reproductive success was assessed. Females preferred larger, aggressive, territorial and experienced males. Correlations between male aggressiveness, aeration and egg survival were significant. During larval care, male aggressiveness was significantly related to larvae survival. Furthermore, intrabucal care and larval survival showed significant correlations with care provided by the experienced, mated and isolated fish. Survival of offspring resulted from mating with experienced and inexperienced males showed significant differences. Correlations between time spent by females with successful males during reproduction and survival rate of eggs and larvae were significant. Females assess the capacity and willingness of males in investing efforts to raise the offspring through their courtship behavior. Experienced and successful males are preferred by females and thereby achieve greater reproductive success.O acará bandeira, Pterophyllum scalareé um ciclídeo nativo da Bacia Amazônica do Brasil, eé exportado como espécie ornamental. Neste estudo foi investigada a importância da experiência dos machos e do sucesso na reprodu

  18. The Utility of Geometric Morphometrics to Elucidate Pathways of Cichlid Fish Evolution

    OpenAIRE

    Michaela Kerschbaumer; Christian Sturmbauer

    2011-01-01

    Fishes of the family Cichlidae are famous for their spectacular species flocks and therefore constitute a model system for the study of the pathways of adaptive radiation. Their radiation is connected to trophic specialization, manifested in dentition, head morphology, and body shape. Geometric morphometric methods have been established as efficient tools to quantify such differences in overall body shape or in particular morphological structures and meanwhile found wide application in evolut...

  19. Acquisition of Lateralized Predation Behavior Associated with Development of Mouth Asymmetry in a Lake Tanganyika Scale-Eating Cichlid Fish.

    Science.gov (United States)

    Takeuchi, Yuichi; Hori, Michio; Tada, Shinya; Oda, Yoichi

    2016-01-01

    The scale-eating cichlid Perissodus microlepis with asymmetric mouth is an attractive model of behavioral laterality: each adult tears off scales from prey fishes' left or right flanks according to the direction in which its mouth is skewed. To investigate the development of behavioral laterality and mouth asymmetry, we analyzed stomach contents and lower jaw-bone asymmetry of various-sized P. microlepis (22 ≤ SLLake Tanganyika. The shapes of the pored scales found in each specimen's stomach indicated its attack side preference. Early-juvenile specimens (SL<45 mm) feeding mainly on zooplankton exhibited slight but significant mouth asymmetry. As the fish acquired scale-eating (45 mm ≤ SL), attack side preference was gradually strengthened, as was mouth asymmetry. Among size-matched individuals, those with more skewed mouths ate more scales. These findings show that behavioral laterality in scale-eating P. microlepis is established in association with development of mouth asymmetry which precedes the behavioral acquisition, and that this synergistic interaction between physical and behavioral literalities may contribute to efficient scale-eating. PMID:26808293

  20. Genetic and environmental effects on the morphological asymmetry in the scale-eating cichlid fish, Perissodus microlepis.

    Science.gov (United States)

    Lee, Hyuk Je; Heim, Valentin; Meyer, Axel

    2015-10-01

    The scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika are a well-known example of an asymmetry dimorphism because the mouth/head is either left-bending or right-bending. However, how strongly its pronounced morphological laterality is affected by genetic and environmental factors remains unclear. Using quantitative assessments of mouth asymmetry, we investigated its origin by estimating narrow-sense heritability (h (2) ) using midparent-offspring regression. The heritability estimates [field estimate: h (2)  = 0.22 ± 0.06, P = 0.013; laboratory estimate: h (2)  = 0.18 ± 0.05, P = 0.004] suggest that although variation in laterality has some additive genetic component, it is strongly environmentally influenced. Family-level association analyses of a putative microsatellite marker that was claimed to be linked to gene(s) for laterality revealed no association of this locus with laterality. Moreover, the observed phenotype frequencies in offspring from parents of different phenotype combinations were not consistent with a previously suggested single-locus two-allele model, but they neither were able to reject with confidence a random asymmetry model. These results reconcile the disputed mechanisms for this textbook case of mouth asymmetry where both genetic and environmental factors contribute to this remarkable case of morphological asymmetry. PMID:26664678

  1. Yolk-sac larval development of the substrate-brooding cichlid Archocentrus nigrofasciatus in relation to temperature.

    Science.gov (United States)

    Vlahos, Nikolaos; Vasilopoulos, Michael; Mente, Eleni; Hotos, George; Katselis, George; Vidalis, Kosmas

    2015-09-01

    In order to conserve and culture the cichlid fish Archocentrus nigrofasciatus, more information about its reproductive biology and its larval behavior and morphogenesis is necessary. Currently, temperatures ranging from 21 to 27 °C are used in ornamental aquaculture hatcheries. Lower temperatures are preferred to reduce the costs of water heating, and 23 °C is usually the selected temperature. However, there is limited information on culturing protocols for ornamental species and most of the information generated on this topic remains scarce. Thus, the present study examines the morphological development of Archocentrus nigrofasciatus during the yolk-sac period up to the age of 100 h post-hatching in relation to 2 temperature regimes used in ornamental aquaculture: a temperature of 27 °C (thermal optimum) and a decreased temperature of 23 °C (thermal tolerance). The results of this study suggest that the 27 °C temperature generates intense morphological changes in yolk-sac development in a shorter period. This has advantages as it reduces the time of yolk-sac larval development, and, thus, minimizes the transition phase to exogenous feeding and maximizes the efficiency at which yolk is converted into body tissues. The present paper provides necessary information to produce freshwater ornamental fish with better practices so as to increase larval survival and capitalize on time for growth. PMID:26201370

  2. Acquisition of Lateralized Predation Behavior Associated with Development of Mouth Asymmetry in a Lake Tanganyika Scale-Eating Cichlid Fish.

    Directory of Open Access Journals (Sweden)

    Yuichi Takeuchi

    Full Text Available The scale-eating cichlid Perissodus microlepis with asymmetric mouth is an attractive model of behavioral laterality: each adult tears off scales from prey fishes' left or right flanks according to the direction in which its mouth is skewed. To investigate the development of behavioral laterality and mouth asymmetry, we analyzed stomach contents and lower jaw-bone asymmetry of various-sized P. microlepis (22 ≤ SL<115 mm sampled in Lake Tanganyika. The shapes of the pored scales found in each specimen's stomach indicated its attack side preference. Early-juvenile specimens (SL<45 mm feeding mainly on zooplankton exhibited slight but significant mouth asymmetry. As the fish acquired scale-eating (45 mm ≤ SL, attack side preference was gradually strengthened, as was mouth asymmetry. Among size-matched individuals, those with more skewed mouths ate more scales. These findings show that behavioral laterality in scale-eating P. microlepis is established in association with development of mouth asymmetry which precedes the behavioral acquisition, and that this synergistic interaction between physical and behavioral literalities may contribute to efficient scale-eating.

  3. Acquisition of Lateralized Predation Behavior Associated with Development of Mouth Asymmetry in a Lake Tanganyika Scale-Eating Cichlid Fish

    Science.gov (United States)

    Takeuchi, Yuichi; Hori, Michio; Tada, Shinya; Oda, Yoichi

    2016-01-01

    The scale-eating cichlid Perissodus microlepis with asymmetric mouth is an attractive model of behavioral laterality: each adult tears off scales from prey fishes’ left or right flanks according to the direction in which its mouth is skewed. To investigate the development of behavioral laterality and mouth asymmetry, we analyzed stomach contents and lower jaw-bone asymmetry of various-sized P. microlepis (22≤SL<115mm) sampled in Lake Tanganyika. The shapes of the pored scales found in each specimen’s stomach indicated its attack side preference. Early-juvenile specimens (SL<45mm) feeding mainly on zooplankton exhibited slight but significant mouth asymmetry. As the fish acquired scale-eating (45mm≤SL), attack side preference was gradually strengthened, as was mouth asymmetry. Among size-matched individuals, those with more skewed mouths ate more scales. These findings show that behavioral laterality in scale-eating P. microlepis is established in association with development of mouth asymmetry which precedes the behavioral acquisition, and that this synergistic interaction between physical and behavioral literalities may contribute to efficient scale-eating. PMID:26808293

  4. Responses of the Mullet, Liza auratus and the Cichlid, Oreochromis niloticus from Lake Manzala (Egypt to Heterophyd Infection

    Directory of Open Access Journals (Sweden)

    E.A. Hassan

    2010-01-01

    Full Text Available In this study, the occurrence of heterophyid infection in two well-known hosts of heterophyd in Egyptian lake (Manzala; the mullet, Liza auratus and the cichlid, Oreochromis niloticus was investigated. Furthermore, the potential factors that possibly affect the occurrence of the infection including host sex, length, weight and seasonal variation were considered. The pathological response of the two fish host to the infection was studied. Results showed that the prevalence, abundance and intensity of infection in the two fish host greatly affected by the factor considered in contradictory way. The responses to infection and the possible effect of the interaction between all the considered factors are discussed in details. In addition, metacercarial infection caused alterations in the histological architecture of the infected tissues and in the composition of the muscle proteins as well which was more pronounced in O. niloticus and L. auratus, respectively. In conclusion, many biological and environmental factors do affect the occurrence of heterophyid infection in addition to the anthropogenic activity. L. auratus was more susceptible to the infection as compared to O. niloticus from the same habitat.

  5. Changes in reproductive life-history strategies in response to nest density in a shell-brooding cichlid, Telmatochromis vittatus

    Science.gov (United States)

    Ota, Kazutaka; Hori, Michio; Kohda, Masanori

    2012-01-01

    To determine whether the appearance of a reproductively parasitic tactic varies, and how this variation affects territorial males of the Lake Tanganyika cichlid fish Telmatochromis vittatus, we examined the reproductive ecology of territorial males in Mtondwe and compared it with that of a neighboring Wonzye population, where nest density differs from that at Mtondwe. In Wonzye, with high nest density, male tactics change with their body size from a territorial to a non-territorial parasitic tactic called piracy in which they conquer several nests defended by territorial males and take over the nests while females are spawning. These "pirate" males could decrease the costs incurred by travelling among nests by exclusively targeting aggregations of nests in close proximity while avoiding separate nests. Territorial males in Wonzye sacrifice the potential higher attractiveness offered by large nests and instead compete for nests farther from neighbors on which pirates less frequently intrude. In contrast, the Mtondwe population had lower nest density and piracy was absent. Given that the success of piracy depends on the close proximity of nests, nest density is likely responsible for the observed variation in the occurrence of piracy between the two populations. Furthermore, in Mtondwe, territorial males competed for larger nests and were smaller than the territorial males in Wonzye. Thus, this lower nest density may free territorial males from the selection pressures for increased size caused by both defense against nest piracy and the need to develop into pirates as they grow.

  6. Structure and dynamics of myxosporean parasites component communities in two freshwater Cichlids in the Chari River (Republic of Chad).

    Science.gov (United States)

    Ousman, Abakar; Félix, Bilong Bilong Charles; Thomas, Njiné; Abraham, Fomena

    2007-03-01

    Myxosporean parasites of two freshwater Tilapia species from the Chari River, Chad Republic, Oreochromis niloticus and Sarotherodon galilaeus, were investigated from November 2001 to October 2002. A total of 360 specimens per Cichlid species were examined. Eleven parasite species were found in both cases with different prevalences. Myxobolus agolus, M. brachysporus, M. clarii, M. cichlidarum, M. heterosporus, M. tilapiae and M. camerounensis in O. niloticus) appeared common while M. equatorialis, M. nyongana (and M. camerounensis in S. galilaeus) were secondary; lastly M. israelensis (and M. kainjiae in O. niloticus) were rare. The gills, fins, eyes and teguments were preferential locations of cysts building pathogens while the kidneys then the gall bladder were most commonly infected by myxosporean spores. In the Chari ecosystem, no significant host sex and size effects were found for the parasite cystic load. A clear seasonal occurrence was observed for most of these pathogens. In the view of pathogenic control, this study raised the necessity in a farm fish station to identify the most important myxosporean species and the period of their potential demographic explosion. PMID:19069850

  7. Social status-dependent nest choice of territorial males under reproductive parasitism in a Lake Tanganyika cichlid Telmatochromis vittatus.

    Science.gov (United States)

    Ota, K; Kohda, M

    2011-03-01

    Field and laboratory studies were conducted to examine how territorial males of a Lake Tanganyika cichlid Telmatochromis vittatus balance the conflicting demands on nest choice between occupying large nests with more females and avoiding reproductive parasitism (nest piracy, which is adopted by the largest males in the population). Pirates less frequently intruded the nests farther from neighbours, perhaps due to the costs associated with travelling between nests. The field experiment showed that territorial male T. vittatus sacrificed the fitness benefits that large nests offer and instead prioritized occupying the nests farther from neighbours on which fewer pirates intruded. The field observations suggested that they adopt different strategies for nest choice according to their relative competitive ability to pirates; the large territorial males, who are size-matched to pirates and can defend their nests against them, compete for larger nests among the more-isolated nests, whereas subordinate territorial males, which are smaller than pirates and thus inferior to them, compete for the more-isolated nests among the less-isolated nests. These findings suggest that the territorial male T. vittatus chooses the more-isolated nests to avoid pirate males at the expense of occupying large nests. PMID:21366567

  8. The use of multiple sources of social information in contest behaviour: testing the social cognitive abilities of a cichlid fish

    Directory of Open Access Journals (Sweden)

    Takashi eHotta

    2015-08-01

    Full Text Available Theory suggests that living in large social groups with dynamic social interactions often favours the evolution of enhanced cognitive abilities. Studies of how animals assess their own contest ability commonly focus on a single cognitive task, and little is known about the diversity or co-occurrence of cognitive abilities in social species. We examined how a highly social cichlid fish Julidochromis transcriptus uses four major cognitive abilities in contest situations; direct experience, winner/loser effects, social eavesdropping and transitive inference (TI. We conducted experiments in which fish assessed the social status of rivals after either direct physical contests or observed contests. Individuals used direct information from a previous physical encounter to re-establish dominance without additional contact, but winner/loser effects were not observed. Social eavesdropping alone was ruled out, but we found that transitive reasoning was used to infer social dominance of other individuals of unknown status. Our results suggest that in stable hierarchical social groups, estimations of contest ability, based on individual recognition pathways such as TI and direct experience, are more prevalent than social eavesdropping or winner/loser effects. We suggest that advanced cognitive abilities might be widespread among highly social fishes, but have previously gone undetected.

  9. Mechanisms of species divergence through visual adaptation and sexual selection:Perspectives from a cichlid model system

    Directory of Open Access Journals (Sweden)

    Martine E. MAAN, Ole SEEHAUSEN

    2010-06-01

    Full Text Available The theory of ecological speciation suggests that assortative mating evolves most easily when mating preferences are directly linked to ecological traits that are subject to divergent selection. Sensory adaptation can play a major role in this process, because selective mating is often mediated by sexual signals: bright colours, complex song, pheromone blends and so on. When divergent sensory adaptation affects the perception of such signals, mating patterns may change as an immediate consequence. Alternatively, mating preferences can diverge as a result of indirect effects: assortative mating may be promoted by selection against intermediate phenotypes that are maladapted to their (sensory environment. For Lake Victoria cichlids, the visual environment constitutes an important selective force that is heterogeneous across geographical and water depth gradients. We investigate the direct and indirect effects of this heterogeneity on the evolution of female preferences for alternative male nuptial colours (red and blue in the genus Pundamilia. Here, we review the current evidence for divergent sensory drive in this system, extract general principles, and discuss future perspectives [Current Zoology 56 (3: 285–299, 2010].

  10. Genetic, comparative genomic, and expression analyses of the Mc1r locus in the polychromatic Midas cichlid fish (Teleostei, Cichlidae Amphilophus sp.) species group.

    Science.gov (United States)

    Henning, Frederico; Renz, Adina Josepha; Fukamachi, Shoji; Meyer, Axel

    2010-05-01

    Natural populations of the Midas cichlid species in several different crater lakes in Nicaragua exhibit a conspicuous color polymorphism. Most individuals are dark and the remaining have a gold coloration. The color morphs mate assortatively and sympatric population differentiation has been shown based on neutral molecular data. We investigated the color polymorphism using segregation analysis and a candidate gene approach. The segregation patterns observed in a mapping cross between a gold and a dark individual were consistent with a single dominant gene as a cause of the gold phenotype. This suggests that a simple genetic architecture underlies some of the speciation events in the Midas cichlids. We compared the expression levels of several candidate color genes Mc1r, Ednrb1, Slc45a2, and Tfap1a between the color morphs. Mc1r was found to be up regulated in the gold morph. Given its widespread association in color evolution and role on melanin synthesis, the Mc1r locus was further investigated using sequences derived from a genomic library. Comparative analysis revealed conserved synteny in relation to the majority of teleosts and highlighted several previously unidentified conserved non-coding elements (CNEs) in the upstream and downstream regions in the vicinity of Mc1r. The identification of the CNEs regions allowed the comparison of sequences from gold and dark specimens of natural populations. No polymorphisms were found between in the population sample and Mc1r showed no linkage to the gold phenotype in the mapping cross, demonstrating that it is not causally related to the color polymorphism in the Midas cichlid. PMID:20449580

  11. Species-specific patterns of nonapeptide brain gene expression relative to pair-bonding behavior in grouping and non-grouping cichlids.

    Science.gov (United States)

    O'Connor, Constance M; Marsh-Rollo, Susan E; Aubin-Horth, Nadia; Balshine, Sigal

    2016-04-01

    Comparative studies have revealed that vasopressin-oxytocin pathways are associated with both pair bonding and grouping behavior. However, the relationship between pair bonding and grouping behavior remains unclear. In this study, our aim was to identify whether two species that differ in grouping behavior display a corresponding difference in their pair bonds, and in the underlying vasopressin-oxytocin hormonal pathways. Using two species of cichlid fishes, the highly social Neolamprologus pulcher and the non-social Telmatochromis temporalis, we measured proximity of pairs during pair bond formation, and then measured social behaviors (proximity, aggression, submission, affiliation) and brain gene expression of isotocin and arginine vasotocin (the teleost homologues of oxytocin and vasopressin, respectively), as well as their receptors, after a temporary separation and subsequent reunion of the bonded pairs. Pairs of the social species spent more time in close proximity relative to the non-social species. Rates of aggression increased in both species following the separation and reunion treatment, relative to controls that were not separated. Overall, whole brain expression of isotocin was higher in the social species relative to the non-social species, and correlated with proximity, submission, and affiliation, but only in the social species. Our results suggest that both a social and a non-social cichlid species have similar behavioral responses to a temporary separation from a mate, and we found no difference in the brain gene expression of measured hormones and receptors based on our separation-reunion treatment. However, our results highlight the importance of isotocin in mediating submissive and affiliative behaviors in cichlid fishes, and demonstrate that isotocin has species-specific correlations with socially relevant behaviors. PMID:26519858

  12. Characterizing the admixed African ancestry of African Americans

    OpenAIRE

    Zakharia, Fouad; Basu, Analabha; Absher, Devin; Assimes, Themistocles L.; Go, Alan S.; Hlatky, Mark A.; Iribarren, Carlos; Knowles, Joshua W.; Li, Jun; Narasimhan, Balasubramanian; Sidney, Steven; Southwick, Audrey; Myers, Richard M.; Quertermous, Thomas; Risch, Neil

    2009-01-01

    Abstract Background Accurate, high-throughput genotyping allows the fine characterization of genetic ancestry. Here we applied recently developed statistical and computational techniques to the question of African ancestry in African Americans by using data on more than 450,000 single-nucleotide polymorphisms (SNPs) genotyped in 94 Africans of diverse geographic origins included in the...

  13. African-Americans and Alzheimer's

    Science.gov (United States)

    ... Share Plus on Google Plus African-Americans and Alzheimer's alz.org | IHaveAlz Introduction 10 Warning Signs Brain ... African-Americans are at a higher risk for Alzheimer's disease. Many Americans dismiss the warning signs of ...

  14. African Cultural Astronomy

    CERN Document Server

    Holbrook, Jarita C; Medupe, R. Thebe; Current Archaeoastronomy and Ethnoastronomy research in Africa

    2008-01-01

    Astronomy is the science of studying the sky using telescopes and light collectors such as photographic plates or CCD detectors. However, people have always studied the sky and continue to study the sky without the aid of instruments this is the realm of cultural astronomy. This is the first scholarly collection of articles focused on the cultural astronomy of Africans. It weaves together astronomy, anthropology, and Africa. The volume includes African myths and legends about the sky, alignments to celestial bodies found at archaeological sites and at places of worship, rock art with celestial imagery, and scientific thinking revealed in local astronomy traditions including ethnomathematics and the creation of calendars. Authors include astronomers Kim Malville, Johnson Urama, and Thebe Medupe; archaeologist Felix Chami, and geographer Michael Bonine, and many new authors. As an emerging subfield of cultural astronomy, African cultural astronomy researchers are focused on training students specifically for do...

  15. African names for American plants

    NARCIS (Netherlands)

    Andel, van T.R.

    2015-01-01

    African slaves brought plant knowledge to the New World, sometimes applying it to related plants they found there and sometimes bringing Old World plants with them. By tracing the linguistic parallels between names for plants in African languages and in communities descended from African slaves, pie

  16. The Struggles over African Languages

    Science.gov (United States)

    Maseko, Pam; Vale, Peter

    2016-01-01

    In this interview, African Language expert Pam Maseko speaks of her own background and her first encounter with culture outside of her mother tongue, isiXhosa. A statistical breakdown of South African languages is provided as background. She discusses Western (originally missionary) codification of African languages and suggests that this approach…

  17. African agricultural trade

    DEFF Research Database (Denmark)

    Jensen, Hans Grinsted; Sandrey, Ron

    2015-01-01

    This article starts with a profile of African agricultural trade. Using the pre-release version 9.2 of the GTAP database, we then show that the results for tariff elimination on intra-African trade are promising, but these tariff barriers are not as significant as the various trade-related barriers...... elimination, non-tariff barrier reductions and time in transit cost reductions are likely to be cumulative and would generate very large gains to Africa. The policy implications are clear: while cooperation will enhance the gains, much of the benefits will result from unilateral actions and regional...

  18. Environment, Health and Climate: Impact of African aerosols

    Science.gov (United States)

    Liousse, C.; Doumbia, T.; Assamoi, E.; Galy-Lacaux, C.; Baeza, A.; Penner, J. E.; Val, S.; Cachier, H.; Xu, L.; Criqui, P.

    2012-12-01

    Fossil fuel and biofuel emissions of particles in Africa are expected to significantly increase in the near future, particularly due to rapid growth of African cities. In addition to biomass burning emissions prevailing in these areas, air quality degradation is then expected with important consequences on population health and climatic/radiative impact. In our group, we are constructing a new integrated methodology to study the relations between emissions, air quality and their impacts. This approach includes: (1) African combustion emission characterizations; (2) joint experimental determination of aerosol chemistry from ultrafine to coarse fractions and health issues (toxicology and epidemiology). (3) integrated environmental, health and radiative modeling. In this work, we show some results illustrating our first estimates of African anthropogenic emission impacts: - a new African anthropogenic emission inventory adapted to regional specificities on traffic, biofuel and industrial emissions has been constructed for the years 2005 and 2030. Biomass burning inventories were also improved in the frame of AMMA (African Monsoon) program. - carbonaceous aerosol radiative impact in Africa has been modeled with TM5 model and Penner et al. (2011) radiative code for these inventories for 2005 and 2030 and for two scenarios of emissions : a reference scenario, with no further emission controls beyond those achieved in 2003 and a ccc* scenario including planned policies in Kyoto protocol and regulations as applied to African emission specificities. In this study we will show that enhanced heating is expected with the ccc* scenarios emissions in which the OC fraction is relatively lower than in the reference scenario. - results of short term POLCA intensive campaigns in Bamako and Dakar in terms of aerosol chemical characterization linked to specific emissions sources and their inflammatory impacts on the respiratory tract through in vitro studies. In this study, organic

  19. Experimentally increased temperature and hypoxia affect stability of social hierarchy and metabolism of the Amazonian cichlid Apistogramma agassizii.

    Science.gov (United States)

    Kochhann, Daiani; Campos, Derek Felipe; Val, Adalberto Luis

    2015-12-01

    The primary goal of this study was to understand how changes in temperature and oxygen could influence social behaviour and aerobic metabolism of the Amazonian dwarf cichlid Apistogramma agassizii. Social hierarchies were established over a period of 96h by observing the social interactions, feeding behaviour and shelter use in groups of four males. In the experimental environment, temperature was increased to 29°C in the high-temperature treatment, and oxygen lowered to 1.0mg·L(-1)O2 in the hypoxia treatment. Fish were maintained at this condition for 96h. The control was maintained at 26°C and 6.6mg·L(-1)O2. After the experimental exposure, metabolism was measured as routine metabolic rate (RMR) and electron transport system (ETS) activity. There was a reduction in hierarchy stability at high-temperature. Aggression changed after environmental changes. Dominant and subdominant fish at high temperatures increased their biting, compared with control-dominant. In contrast, hypoxia-dominant fish decreased their aggressive acts compared with all other fish. Shelter use decreased in control and hypoxic dominant fish. Dominant fish from undisturbed environments eat more than their subordinates. There was a decrease of RMR in fish exposed to the hypoxic environment when compared with control or high-temperature fish, independent of social position. Control-dominant fish had higher RMR than their subordinates. ETS activity increased in fish exposed to high temperatures; however, there was no effect on social rank. Our study reinforces the importance of environmental changes for the maintenance of hierarchies and their characteristics and highlights that most of the changes occur in the dominant position. PMID:26387464

  20. Effect of hypergravity on the Ca/Sr composition of developing otoliths of larval cichlid fish (Oreochromis mossambicus).

    Science.gov (United States)

    Anken, R H; Ibsch, M; Breuer, J; Rahmann, H

    2001-02-01

    The amounts of calcium and strontium were measured by inductively coupled plasma mass spectrometry (ICP-MS) in saccular and utricular inner ear otoliths (sagittae and lapilli, respectively) of developing cichlid fish. These fish had been maintained for 22 days at 3-g hypergravity conditions within a centrifuge. During this time-span, the animals completed their ontogenetic development from hatch to the free-swimming stage. Neither the morphogenetic development nor the timely onset and gain of performance of the swimming behaviour was impaired by the experimental conditions. Experimental and control animals also did not differ concerning their size (total length). ICP-MS revealed that the otoliths contained significantly less calcium (in microg/otolith) after hyper-g exposure compared to parallelly raised 1-g control specimens (lapilli: 0.74+/-0.21 vs. 1.16+/-0.41; sagittae: 2.09+/-0.49 vs. 2.76+/-0.47). The content of strontium (in microg/otolith: lapilli: 0.0044+/-0.0023 vs. 0.0022+/-0.0013; sagittae: 0.0094+/-0.0026 vs. 0.0081+/-0.0016) and, consequently, the Sr/Ca ratio (Sr/Cax100) was increased (lapilli: 0.607+/-0.267 vs. 0.201+/-0.12; sagittae: 0.439+/-0.093 vs. 0.301+/-0.086). Since the calcium content can be taken as a proxy for otolith weight, and because parallelly undertaken morphometric investigations revealed smaller otoliths (maximum radius and surface area) due to hyper-g exposure, the results suggest that the growth of otoliths at hyper-g is slowed down. Since the concentration of trace elements incorporated into otoliths is likely based on the composition of the respective protein matrix, our findings suggest that the protein metabolism is affected by hypergravity. PMID:11223398

  1. Ecological and Evolutionary Consequences of Color- and Trophic Polymorphisms in Cichlid Fishes

    OpenAIRE

    Kusche, Henrik

    2013-01-01

    How the exuberant diversity on our planet arose is still a question of central interest in biology. Rapidly diversifying species complexes that experience adaptive radiation have always been prime study targets to infer the underlying mechanisms of divergence. Young species-rich systems that display ongoing diversification in multiple replicates are of particular relevance, because different stages of divergence are likely to be found, ranging from incipient speciation to stable species assem...

  2. Deepening African Ties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chinese President Hu Jintao has just embarked on his state visits to eight African countries that will take him to both the northern and southern tips of the continent. This is his first trip abroad this year, and also his third visit to Africa

  3. East African institutions

    DEFF Research Database (Denmark)

    Nordby, Johannes Riber; Jacobsen, Katja

    For the past decade security in East Africa has gained focus internationally. However there is a growing ambition among African states to handle such issues by themselves, sometimes through regional institutions. This has been supported by many Western states but potential risks are often forgotten....

  4. African Women Writing Resistance

    Institute of Scientific and Technical Information of China (English)

    Jennifer Browdy de Hernandez; Pauline Dongala; Omotayo; Jolaosho; Anne Serafin

    2011-01-01

    AFRICAN Women Writing Resistance is the first transnational anthology to focus on women's strategies of resistance to the challenges they face in Africa today.The anthology brings together personal narratives,testimony,interviews,short stories,poetry,performance scripts,folktales and lyrics.

  5. African Women Writing Resistance

    Institute of Scientific and Technical Information of China (English)

    Jennifer; Browdy; de; Hernandez; Pauline; Dongala; Omotayo; Jolaosho; Anne; Serafin

    2011-01-01

    An Anthology of Contemporary Voices AFRICAN Women Writing Resistance is the first transnational anthology to focus on women’s strategies of resistance to the challenges they face in Africa today.The anthology brings together personal narratives,testimony,interviews, short stories,po-

  6. West African Antislavery Movements

    DEFF Research Database (Denmark)

    Hahonou, Eric Komlavi; Pelckmans, Lotte

    2011-01-01

    In the context of liberalization of West African political regimes, the upsurge of audacious political entrepreneurs who want to end chattel slavery in their nation-state, resulted in the legal criminalisation of slavery in both Mauritania (2007) and Niger (2003) and in a proposal to revise the...... cultures (or ‘mentalities’) go hand in hand....

  7. Immunizations and African Americans

    Science.gov (United States)

    ... Program Grants Other Grants Planning and Evaluation Grantee Best Practices Black/African American Asthma Cancer Chronic Liver Disease ... 13 to 17 years who ever received the human papillomavirus (HPV) vaccination, 2014 - Males # doses ... 240-453-2882 Office of Minority Health Resource Center Toll Free: 1-800-444-6472 / Fax: ...

  8. The African Union

    DEFF Research Database (Denmark)

    Mandrup, Thomas; Mandrup, Bjørn

    2009-01-01

    . Moreover, the ‘African Security Architecture’, of which it is the central component, also includes sub-regional organisations to which responsibility is to be devolved for dealing with armed confl ict and other matters. These so-called Regional Economic Communities (RECs) are, likewise, constantly changing...

  9. African tick bite fever

    DEFF Research Database (Denmark)

    Johansen, Jakob Aaquist; Thybo, Søren

    2011-01-01

    The incident of spotted fever imported to Denmark is unknown. We present a classic case of African Tick Bite Fever (ATBF) to highlight a disease, which frequently infects wildlife enthusiasts and hunters on vacation in South Africa. ATBF has a good prognosis and is easily treated with doxycyclin...

  10. Male mating preferences pre-date the origin of a female trait polymorphism in an incipient species complex of Lake Victoria cichlids.

    Science.gov (United States)

    Pierotti, M E R; Seehausen, O

    2007-01-01

    Disruptive sexual selection on colour patterns has been suggested as a major cause of diversification in the cichlid species flock of Lake Victoria. In Neochromis omnicaeruleus, a colour and sex determination polymorphism is associated with a polymorphism in male and female mating preferences. Theoretical work on this incipient species complex found conditions for rapid sympatric speciation by selection on sex determination and sexual selection on male and female colour patterns, under restrictive assumptions. Here we test the biological plausibility of a key assumption of such models, namely, the existence of a male preference against a novel female colour morph before its appearance in the population. We show that most males in a population that lacks the colour polymorphism exhibit a strong mating preference against the novel female colour morph and that reinforcement is not a likely explanation for the origin of such male preferences. Our results show that a specific condition required for the combined action of selection on sex determination and sexual selection to drive sympatric speciation is biologically justified. Finally, we suggest that Lake Victoria cichlids might share an ancestral female recognition scheme, predisposing colour monomorphic populations/species to similar evolutionary pathways leading to divergence of colour morphs in sympatry. PMID:17210017

  11. Female genital mutilation in African and African American women's literature

    Directory of Open Access Journals (Sweden)

    Darja Marinšek

    2007-12-01

    Full Text Available The article builds on the existing dispute between African and African American women writers on the competence of writing about female genital mutilation (FGM, and tries to determine the existence and nature of the differences between the writings of these two groups. The author uses comparative analysis of two popular African and African American novels, comparing their ways of describing FGM, its causes and consequences, the level ob objectivity and the style of the narrations.This is followed by a discussion on the reasons for such differences, incorporating a larger circle of both African and African American women authors, at the same time analysing the deviance within the two groups. While the differences between African American writers are not that great, as they mostly fail to present the issue from different points of view, which is often the result of their lack of direct knowledge of the topic, African authors' writing is in itself discovered to be ambivalent and not at all invariable. The reasons for such ambivalence are then discussed in greater context, focusing on the effect of the authors' personal contact with circumcision as well as their knowledge and acceptance of Western values. The author concludes by establishing the African ambivalent attitude towards FGM, which includes different aspects of the issue, as the most significant difference between their and African American writers' description of this practice.

  12. Leadership in the African context

    Directory of Open Access Journals (Sweden)

    M. Masango

    2002-08-01

    Full Text Available The Western world has always viewed the African continent as plagued by corruption; dictatorship; military coups; rebellious leaders; greediness; misuse of power; and incompetent, politically unstable leaders - in effect, suspicious leaders who undermine their own democracies. This paper analyzes African leadership and its impact by concentrating on three historical eras, namely; the African Religious era; the Christian era, and the era of Globalization. These affected African leadership. In addition, many brilliant minds left the continent in search of greener pastures. A review of these three eras will help us understand how leadership shifted from African values into Western concepts. The role of missionaries lead African people to live with both an African and a Western concept of life. In spite of the above problems, our past leaders did their best in addressing the difficulties they faced during the three eras. African concepts of leadership were often regarded as barbaric and uncultured. Structures were evaluated by Western standards. Due to globalisation, African leaders, through programmes like NEPAD, are going back to basics, drawing on African concepts of unity among its leadership. Effectiveness or life-giving leadership is emerging and empowering villagers/communities in the continent. This type of leadership is innovative and has brought new hope for the continent.

  13. The first joint congress of the South African Biochemical Society, South African Genetics Society and the South African Society for Microbiology at the University of the Witwatersrand, 29 June-4 July 1986

    International Nuclear Information System (INIS)

    The South African Biochemical Society, South African Genetics Society and the South African Society for Microbiology held a joint congress at the University of the Witwatersrand from 29 June - 4 July 1986. The papers delivered cover subjects such as Molecular biology, Genetics, Biochemistry, Medical biochemistry, Physiology, Zoology and Isotope and radiation sciences. Different isotopes are used in labelling studies of enzymes, nutrition, metabolism, viruses, bacteria and other biological assays done in the fields of Biochenmistry, Genetics and Microbiology. This work contains only the abstracts of these papers

  14. The genetic structure and history of Africans and African Americans

    OpenAIRE

    Tishkoff, Sarah A; Reed, Floyd A; Friedlaender, Françoise R; Ehret, Christopher; Ranciaro, Alessia; Froment, Alain; Hirbo, Jibril B.; Awomoyi, Agnes A; Bodo, Jean-Marie; Doumbo, Ogobara; Ibrahim, Muntaser; Juma, Abdalla T; Kotze, Maritha J.; Lema, Godfrey; Moore, Jason H.

    2009-01-01

    Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic p...

  15. Steps to African Development

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The development of Africa is vital to the world’s sustainable development.However,African countries still face key challenges in achieving the meaningful expansion of their economies.At the High-Level Symposium on China-Africa Investment Cooperation in Xiamen,southeast China’s Fujian Province,held from September 8 to 10,Chen Deming,Minister of Commerce of China,elaborates on these challenges and sees

  16. Biofuels: The African experience

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo, L.A.; Nkolo, M. [German Agency for Technical Cooperation GTZ, Delegation Regionale des Eaux et Forets, Bertoua (Cameroon)

    2009-07-01

    In July 2006, the African Non-Petroleum Producers Association was formed in Senegal, Africa to develop alternative energy sources. It involved 13 of Africa's poorest nations, who joined forces to become global suppliers of biofuels, and some have set mandatory mixing of ethanol into gasoline. Although several biofuel production projects have been launched in western Africa, many of the new projects and plantations have not yet reached maturity due to the time lag between plantation and full-scale production, which is about 6 years. Major projects that could be producing significant quantities of biofuels in the next few years are not yet reflected in production statistics. Although ethanol is not yet being produced in large quantities in Africa, short-term opportunities exist. Countries in the South African Development Community are using molasses from the sugar can industry to produce ethanol. Biodiesel is also not currently produced on a significant scale in western Africa, but several other countries are gaining experience with cotton and palm oil resources, and Jatropha. Biomass residue also represents a large potential for all African countries involved in timber production. Unlike biodiesel production, land use conflicts are not an issue with biomass residue production.

  17. Diversity among African pygmies.

    Directory of Open Access Journals (Sweden)

    Fernando V Ramírez Rozzi

    Full Text Available Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies.

  18. Institution Building for African Regionalism

    OpenAIRE

    Khadiagala, Gilbert M.

    2011-01-01

    Since the 1960s, African states have embraced regional integration as a vital mechanism for political cooperation and for pooling resources to overcome problems of small and fragmented economies. In building meaningful institutions for regionalism, however, Africans have faced the challenges of reconciling the diversities of culture, geography, and politics. As a result, African regional institutions are characterized by multiple and competing mandates and weak institutionalization. This stud...

  19. African-Americans and Heart Disease, Stroke

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More African-Americans and Heart Disease, Stroke Updated:Apr 18, ... of getting those diseases are even higher for African-Americans. The good news is, African-Americans can ...

  20. Chronic Liver Disease and African Americans

    Science.gov (United States)

    ... American > Chronic Liver Disease Chronic Liver Disease and African Americans Among African Americans, chronic liver disease is a ... white women. At a glance – Cancer Rates for African Americans (2008-2012) Cancer Incidence Rates per 100,000 – ...

  1. Sampling genetic diversity in the sympatrically and allopatrically speciating Midas cichlid species complex over a 16 year time series

    Directory of Open Access Journals (Sweden)

    Bunje Paul ME

    2007-02-01

    Full Text Available Abstract Background Speciation often occurs in complex or uncertain temporal and spatial contexts. Processes such as reinforcement, allopatric divergence, and assortative mating can proceed at different rates and with different strengths as populations diverge. The Central American Midas cichlid fish species complex is an important case study for understanding the processes of speciation. Previous analyses have demonstrated that allopatric processes led to species formation among the lakes of Nicaragua as well as sympatric speciation that is occurring within at least one crater lake. However, since speciation is an ongoing process and sampling genetic diversity of such lineages can be biased by collection scheme or random factors, it is important to evaluate the robustness of conclusions drawn on individual time samples. Results In order to assess the validity and reliability of inferences based on different genetic samples, we have analyzed fish from several lakes in Nicaragua sampled at three different times over 16 years. In addition, this time series allows us to analyze the population genetic changes that have occurred between lakes, where allopatric speciation has operated, as well as between different species within lakes, some of which have originated by sympatric speciation. Focusing on commonly used genetic markers, we have analyzed both DNA sequences from the complete mitochondrial control region as well as nuclear DNA variation at ten microsatellite loci from these populations, sampled thrice in a 16 year time period, to develop a robust estimate of the population genetic history of these diversifying lineages. Conclusion The conclusions from previous work are well supported by our comprehensive analysis. In particular, we find that the genetic diversity of derived crater lake populations is lower than that of the source population regardless of when and how each population was sampled. Furthermore, changes in various estimates of

  2. The African Diaspora, Civil Society and African Integration

    DEFF Research Database (Denmark)

    Opoku-Mensah, Paul Yaw

    This paper, a work-in-progress, makes a contribution to the discussions on the appropriate modalities for incorporating the African diaspora in the African integration project.  It argues that the most appropriate entry points for incorporating the African diaspora into the integration project...... might not, necessarily, be in the formal political structures, although this is important. To the contrary, the most effective and sustainable might be within civil society---that is the links between the peoples and organizations of Africa and the diaspora. Using the case of the African academy-- as an...... institution of civil society--- the paper outlines a conceptual framework for incorporating the diaspora into the African integration project....

  3. Aggressive interactions between the invasive Rio Grande cichlid (Herichthys cyanoguttatus) and native bluegill (Lepomis macrochirus), with notes on redspotted sunfish (Lepomis miniatus)

    Science.gov (United States)

    Lorenz, O. Thomas; O' Connell, Martin T.; Schofield, Pamela J.

    2010-01-01

    The Rio Grande cichlid (Herichthys cyanoguttatus) has been established in the Greater New Orleans Metropolitan area for at least 20 years, and its effect on native fishes is unknown. Behavioral trials were performed to determine if aggressive interactions occur between invasive H. cyanoguttatus and native bluegill (Lepomis macrochirus). When defending a territory as the resident, L. macrochirus were markedly aggressive, averaging 11.6 aggressive actions per lO-min behavioral trial. In contrast, L. macrochirus were extremely passive as invaders, with 0.5 aggressive actions per trial. Herichthys cyanoguttatus were equally aggressive as residents and as invaders, averaging 4.9 and 6.0 aggressive actions per trial, respectively. Herichthys cyanoguttatus interacted aggressively with native species whether they held territory or not, indicating that this invasive species may have fundamentally different strategies of aggression compared with native L. macrochirus. These differences may explain the continued success of H. cyanoguttatus as an invasive fish in southeastern Louisiana.

  4. Social cohesiveness of convict cichlid fish (Cichlasoma nigrofasciatum Guenther) after irradiation of parental spermatogonia and oogonia with different doses of x-rays

    International Nuclear Information System (INIS)

    Comparisons of social cohesiveness were made between F1 convict cichlids derived from gonial germ cells which were exposed to 0, 250, 500, 750, 1000, or 2000 R of x-rays. The cohesiveness was determined by counting the distribution of each ten fish of every F1 group among 12 equal squares within a shallow test tank measuring 80 by 60 by 20 cm. While an increase in cohesiveness was detected in F1 males, as compared to the controls after irradiation with 500 R, the cohesiveness of F1 females decreased after 750 and 2000 R. The increase in male cohesiveness may be associated with a reduction of intermale aggressiveness as found in previous studies

  5. Booster for African Economy

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China’s investment is fueling African growth SINCE 2000,driven by the Forum on China-Africa Cooperation,China’s foreign direct investment(FDI) in Africa has been growing rapidly.In the face of the global financial crisis,which led to global FDI flows falling,China’s investment in Africa has been on a steady, upbeat rise without any interruption.In 2009,China’s direct investment in Africa reached $1.44 billion,of which nonfinancial direct investment soared by 55.4 percent from the previous year.Africa

  6. African Conservation Tillage Network Website

    OpenAIRE

    African Conservation Tillage Network (ACT)

    2009-01-01

    Metadata only record Maintained by the African Conservation Tillage Network (ACT), this website provides information on Conservation Agriculture in an African context and gathered by stakeholders (NGOs) native to the continent. Resources on projects, practices, reports, and training courses are provided.

  7. A Call to African Unity

    DEFF Research Database (Denmark)

    Muchie, Mammo

    This month's paper, written by Professor Mammo Muchie, examines the necessity for a pan-African monetary union.  Professor Muchie argues for the "the creation of a unified African strategy and unified approach to dealing with the outside donor world by neutralising the poison of money as honey th...

  8. African Diaspora Associations in Denmark

    DEFF Research Database (Denmark)

    Vammen, Ida Marie; Trans, Lars Ove

    2011-01-01

    Since the early 1990s, an increasing number of African migrants have come to Denmark, where they have formed a large number of migrant associations. This chapter presents selected findings from a comprehensive survey of African diaspora associations in Denmark and focuses specifically on their...

  9. Occurrence of Sciadicleithrum mexicanum Kritsky, Vidal-Martinez et Rodríguez-Canul, 1994 (Monogenea: Dactylogyridae) in the Cichlid Cichlasoma urophthalmus from a flooded quarry in Yucatan, Mexico

    OpenAIRE

    E. F. Mendoza-Franco; V. Vidal-Martínez; R. Simá-Álvarez; R. Rodríguez-Canul; C. Vivas-Rodríguez; Scholz, T

    1995-01-01

    Cichlids, Cichlasoma urophthalmus, collected in a flooded quarry in the Yucatan Peninsula, Mexico, from January through June 1992, had high levels of infection with the ancyrocephaline Sciadicleithrum mexicanum (Monogena: Dactylogyridade) in all montlhly samples. Neither occurrence nor maturation of the worms eshibited any pronounced monthly fluctuation. The infection rate was found to be sizedependent, greater in longer fish. The worms occurred on primary lamellae of gill filaments of all ar...

  10. Bioenergy and African transformation.

    Science.gov (United States)

    Lynd, Lee R; Sow, Mariam; Chimphango, Annie Fa; Cortez, Luis Ab; Brito Cruz, Carlos H; Elmissiry, Mosad; Laser, Mark; Mayaki, Ibrahim A; Moraes, Marcia Afd; Nogueira, Luiz Ah; Wolfaardt, Gideon M; Woods, Jeremy; van Zyl, Willem H

    2015-01-01

    Among the world's continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some important lessons. In Brazil, social development, agricultural development and food security, and bioenergy development have been synergistic rather than antagonistic. Realizing similar success in African countries will require clear vision, good governance, and adaptation of technologies, knowledge, and business models to myriad local circumstances. Strategies for integrated production of food crops, livestock, and bioenergy are potentially attractive and offer an alternative to an agricultural model featuring specialized land use. If done thoughtfully, there is considerable evidence that food security and economic development in Africa can be addressed more effectively with modern bioenergy than without it. Modern bioenergy can be an agent of African transformation, with potential social benefits accruing to multiple sectors and extending well beyond energy supply per se. Potential negative impacts also cut across sectors. Thus, institutionally inclusive multi-sector legislative structures will be more effective at maximizing the social benefits of bioenergy compared to institutionally exclusive, single-sector structures. PMID:25709714

  11. Mitochondrial phylogeography of rock-dwelling cichlid fishes reveals evolutionary influence of historical lake level fluctuations of Lake Tanganyika, Africa

    OpenAIRE

    Verheyen, Erik; Rüber, Lukas; Snoeks, Jos; Meyer, Axel

    1996-01-01

    The East African Lakes Tanganyika, Malawi and Victoria each harbour hundreds of endemic invertebrate and vertebrate species. Inferences about the ecological and evolutionary processes responsible for the origin of these species flocks will only be possible when they are made within historical and comparative frameworks. Specifically, the relative importance of intrinsic characteristics and extrinsic factors may offer information about the processes that drive diversification and speciation in...

  12. Court stories in selected African short narratives

    OpenAIRE

    E. Yewah

    1994-01-01

    This article attempts to cross-examine African Literature and African costumary, Islamic and inherited colonial laws. It opens a new topic in the study of African literature by showing how legal discourses are inscribed in certain African narratives and how these discourses link the narratives to the overall context of their production.

  13. 2002 Sino-African SHP Training Workshop

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The 2002 Sino-African SHP Training Workshop was held from 10 May to 18 June 2002 at Hangzhou Regional Center for Small Hydro Power(HRC). Attended altogether 9 participants from 5 African countries, i.e. Burundi, Nigeria, South African, Tanzania and Tunisia. This is the second training workshop on SHP that HRC conducted for African countries.

  14. Assimilation Differences among Africans in America.

    Science.gov (United States)

    Dodoo, F. Nii-Amoo

    1997-01-01

    Census data (1990) indicate that male African immigrants earn more than their Caribbean-born counterparts or native-born African Americans, but controlling for relevant earnings-related endowments erases the African advantage and elevates Caribbean earnings above those of the other groups. Also, African (but not Caribbean) university degree…

  15. Phylogeny and biogeography of 91 species of heroine cichlids (Teleostei: Cichlidae) based on sequences of the cytochrome b gene.

    Science.gov (United States)

    Pérez, Gustavo A Concheiro; Rícan, Oldrich; Ortí, Guillermo; Bermingham, Eldredge; Doadrio, Ignacio; Zardoya, Rafael

    2007-04-01

    Heroini constitute the second largest tribe of Neotropical cichlids and show their greatest diversity in Mesoamerica. Although heroine species are morphologically and ecologically very diverse, they were all historically assigned to one single genus, Cichlasoma that was never formally revised from a phylogenetic point of view. Here, we present the most comprehensive molecular phylogeny of the tribe Heroini to date, based on the complete DNA sequence of the mitochondrial gene cytochrome b, and the analysis of 204 individuals representing 91 species. Phylogenetic analyses did not support the monophyly of heroines because the genus Pterophyllum was placed as the sister group of all remaining heroines plus cichlasomatines. However, the recovered relative position of Pterophyllum was without strong statistical support. Within the remaining heroines, Hyspelecara and Hoplarchus are recovered with low support in a basal position with respect to a clade that includes Heros, Uaru, Mesonauta, and Symphysodon, and the circumamazonian (CAM) heroines. The first clade is restricted to South America. The largest clade of heroines, the CAM heroines, include more than 85% of the species within the tribe. This clade is mostly Mesoamerican, but also contains four species found in the Greater Antilles (Nandopsis), and three genera found in South America (the 'Heros' festae group, Australoheros, and Caquetaia). Up to eight major lineages can be recovered within the CAM heroines, but the phylogenetic relationships among them remain unresolved. Two large suprageneric groups can be distinguished, the amphilophines and the herichthyines. The amphilophines include Amphilophus, Archocentrus, Hypsophrys, Neetroplus, Parachromis, Petenia, and five additional unnamed genera (the 'Heros' istlanus group, the 'Amphilophus' calobrensis group, the 'Heros' urophthalmus group, the 'Heros' wesseli group, and the 'Heros' sieboldii group). The herichthyines include the crown-group herichthyines

  16. How student teachers understand African philosophy

    OpenAIRE

    Matsephe M. Letseka; Elza Venter

    2012-01-01

    The question ‘What constitutes African philosophy?’ was first raised with the publication of Placide Tempels’s seminal work Bantu philosophy in 1959. Tempels’s book inevitably elicited considerable critical response from African philosophers, which culminated in a wide range of publications such as Wiredu’s (1980) Philosophy and an African culture, Hountondji’s (1983) African philosophy: Myth and reality, Oruka’s (1990) Sage philosophy: Indigenous thinkers and modern debate on African philoso...

  17. African Ethnobotany in the Americas

    OpenAIRE

    Zent, Egleé L

    2013-01-01

    Review of African Ethnobotany in the Americas. Edited by Robert Voeks and John Rashford. 2013. Springer. Pp. 429, 105 illustrations, 69 color illustrations. $49.95 (paperback). ISBN 978‐1461408352.

  18. Mental Health and African Americans

    Science.gov (United States)

    ... Program Grants Other Grants Planning and Evaluation Grantee Best Practices Black/African American Asthma Cancer Chronic Liver Disease Diabetes Heart Disease Hepatitis HIV/AIDS Immunizations Infant Heath & Mortality Mental Health Obesity Organ and Tissue Donation Stroke Stay Connected ...

  19. African Ethnobotany in the Americas

    Directory of Open Access Journals (Sweden)

    Egleé L. Zent

    2013-10-01

    Full Text Available Review of African Ethnobotany in the Americas. Edited by Robert Voeks and John Rashford. 2013. Springer. Pp. 429, 105 illustrations, 69 color illustrations. $49.95 (paperback. ISBN 978‐1461408352.

  20. Twin Sessions Through African Eyes

    Institute of Scientific and Technical Information of China (English)

    Ni Yanshuo

    2012-01-01

    Every year journalists from around China and the world flock to Beijing in March to cover the sessions of the National People's Congress (NPC) and the Chinese People's Political Consultative Conference (CPPCC), known as the lianghui, or twin sessions. With the deepening of Sino-African relations in the past decades, an increasing number of African journalists are involved in reporting China's lianghui to their audiences in Africa.

  1. The Good African Society Index

    OpenAIRE

    Ferdi Botha

    2014-01-01

    This paper constructs a Good Society Index for 45 African countries, termed the Good African Society Index (GASI). The GASI consists of nine main indexes: (i) economic sustainability, (ii) democracy and freedom, (iii) child well-being, (iv) environment and infrastructure, (v) safety and security, (vi) health and health systems, (vii) integrity and justice, (viii) education, and (xi) social sustainability and social cohesion. Each component is split into four sub-components for a total of 36 i...

  2. Training in African aquaculture development

    OpenAIRE

    Brummett, R. E.

    1994-01-01

    The article focuses on the types of training needed in African aquaculture development. The author suggested that rather than needing less training, extension agents and others who operate in the idiosyncratic world of the poor African farmer, need a far deeper understanding of fish culture (particularly the basics of pond dynamics and ecology) than do those who can take advantage of industrialized-country infrastructure.

  3. Use of hematological parameters to assess the efficiency of quince (Cydonia oblonga Miller) leaf extract in alleviation of the effect of ultraviolet--A radiation on African catfish Clarias gariepinus (Burchell, 1822).

    Science.gov (United States)

    Osman, Alaa G M; Koutb, Mostafa; Sayed, Alaa El-Din H

    2010-04-01

    The present study aimed to elucidate the negative impacts of UVA on some biochemical and hematological variables of the economically important African catfish, Clarias gariepinus and investigates the putative role of quince (Cydonia oblonga Miller) leaf extract in protection and/or alleviation of such negative impacts. Changes in the hematological and blood biochemical values often reflect alteration of physiological state. Blood parameters can be useful for the measurement of physiological disturbances in stressed fish and thus provide information about the level of damage in the fish. We found a significant (P<0.05) decrease in the red blood cell counts, hemoglobin and hematocrit in the groups exposed to UVA compared to the control groups. Exposure to UVA induced marked red cell shrinkage (increased mean cell hemoglobin concentration) and showed an elevation in mean cell volume and mean cell hemoglobin in the blood of the exposed fish compared to the control. A significant (P<0.05) reduction in the total white blood cells was recorded in the exposed fish compared to the control. The biochemical parameters (blood glucose, total plasma protein, blood cholesterol, plasma creatinine, aspartic amino transferase and alanine amino transferase) exhibited a significant increase in the blood of fish exposed to UVA. Methanolic extract of quince leaf before ripening of the fruits was analyzed by GC/MS. To investigate the biological impact of this extract and its biologically active components, this extract was tested for its putative role in alleviation of UVA effect on catfish. Quince leaf extract had the ability to prevent hematotoxic stress induced by UVA and resulted in enhancement of the immune system of catfish represented by significant (P<0.05) increase in the number of white blood cells and lymphocytes of the catfish. Quince extract also protected the red blood cells from UVA damage. To our knowledge this is the first report of the effect of quince leaf extract on

  4. Aerosol interactions with African/Atlantic climate dynamics

    International Nuclear Information System (INIS)

    Mechanistic relationships exist between variability of dust in the oceanic Saharan air layer (OSAL) and transient changes in the dynamics of Western Africa and the tropical Atlantic Ocean. This study provides evidence of possible interactions between dust in the OSAL region and African easterly jet–African easterly wave (AEJ–AEW) system in the climatology of boreal summer, when easterly wave activity peaks. Synoptic-scale changes in instability and precipitation in the African/Atlantic intertropical convergence zone are correlated with enhanced aerosol optical depth (AOD) in the OSAL region in response to anomalous 3D overturning circulations and upstream/downstream thermal anomalies at above and below the mean-AEJ level. Upstream and downstream anomalies are referred to the daily thermal/dynamical changes over the West African monsoon region and the Eastern Atlantic Ocean, respectively. Our hypothesis is that AOD in the OSAL is positively correlated with the downstream AEWs and negatively correlated with the upstream waves from climatological perspective. The similarity between the 3D pattern of thermal/dynamical anomalies correlated with dust outbreaks and those of AEWs provides a mechanism for dust radiative heating in the atmosphere to reinforce AEW activity. We proposed that the interactions of OSAL dust with regional climate mainly occur through coupling of dust with the AEWs. (paper)

  5. Aerosol interactions with African/Atlantic climate dynamics

    Science.gov (United States)

    Hosseinpour, F.; Wilcox, E. M.

    2014-07-01

    Mechanistic relationships exist between variability of dust in the oceanic Saharan air layer (OSAL) and transient changes in the dynamics of Western Africa and the tropical Atlantic Ocean. This study provides evidence of possible interactions between dust in the OSAL region and African easterly jet-African easterly wave (AEJ-AEW) system in the climatology of boreal summer, when easterly wave activity peaks. Synoptic-scale changes in instability and precipitation in the African/Atlantic intertropical convergence zone are correlated with enhanced aerosol optical depth (AOD) in the OSAL region in response to anomalous 3D overturning circulations and upstream/downstream thermal anomalies at above and below the mean-AEJ level. Upstream and downstream anomalies are referred to the daily thermal/dynamical changes over the West African monsoon region and the Eastern Atlantic Ocean, respectively. Our hypothesis is that AOD in the OSAL is positively correlated with the downstream AEWs and negatively correlated with the upstream waves from climatological perspective. The similarity between the 3D pattern of thermal/dynamical anomalies correlated with dust outbreaks and those of AEWs provides a mechanism for dust radiative heating in the atmosphere to reinforce AEW activity. We proposed that the interactions of OSAL dust with regional climate mainly occur through coupling of dust with the AEWs.

  6. The New African Civil-Military Relations

    DEFF Research Database (Denmark)

    the lead author accorded the responsibility of organizing a Session on ACMR. From amongst some of the exciting Abstracts presented, authors submitted these as full chapters for this book which captures International African Studies Perspectives, managed by the African Public Policy & Research...... on the African continent to embark upon the New African Civil Military Relations (ACMR). In the last decade and half, the implosion of African states exposed to forces of democratization has escalated, manifest in Algeria, Egypt, Mali, Madagascar, Somalia, South Sudan, Central African Republic and...

  7. Disarmament: the African perspective

    International Nuclear Information System (INIS)

    Disarmament is now generally accepted as the process of reduction in the size of, and expenditures on, armed forces, the destruction or dismantling of weapons, whether deployed or stockpiled, the progressive elimination of the capacity to produce new weapons and the release and integration into civilian life of military personnel. To realize this objective, the nations of the world have been advocating such measures as the establishment of nuclear weapon-free zones, non-proliferation, limitation of the arms trade, reduction of military budgets, and confidence-building measures. To ensure general and complete elimination of arms, there has been widespread recognition of the need to link the disarmament process with other political as well as socio-economic problems of the world such as the need for security, good relations between states and development of a system of peaceful settlement of disputes. Other measures that have been considered to be relevant in boosting the disarmament process include the role of the general public in putting pressure on their respective governments with a view to accelerating and realizing disarmament objectives. Africans have presented to the world a strong case for global disarmament

  8. East African Rift

    Science.gov (United States)

    2008-01-01

    Places where the earth's crust has formed deep fissures and the plates have begun to move apart develop rift structures in which elongate blocks have subsided relative to the blocks on either side. The East African Rift is a world-famous example of such rifting. It is characterized by 1) topographic deep valleys in the rift zone, 2) sheer escarpments along the faulted walls of the rift zone, 3) a chain of lakes within the rift, most of the lakes highly saline due to evaporation in the hot temperatures characteristic of climates near the equator, 4) voluminous amounts of volcanic rocks that have flowed from faults along the sides of the rift, and 5) volcanic cones where magma flow was most intense. This example in Kenya displays most of these features near Lake Begoria. The image was acquired December 18, 2002, covers an area of 40.5 x 32 km, and is located at 0.1 degrees north latitude, 36.1 degrees east longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  9. Need for cooperation among IRPA associate societies in African

    International Nuclear Information System (INIS)

    Radiation is an inescapable part of the natural environment, and it is also produced artificially for a variety of unique applications in health, environmental studies, industry, etc. Our present and future lifestyles are unsustainable without peaceful applications of radiation technologies. Events around the world continue to indicate an increasing need for nuclear energy. Africa: A high level African Regional Conference on the contribution of Nuclear Energy to Peace and Sustainable Development (January 2007, Algiers), recommended that African countries should promote the acquisition of scientific know-how and the necessary infrastructure for the peaceful use of nuclear energy. This recommendation was adopted by the Executive council of Ministers during the 8th African Union (AU) summit of January 2007. 6 Many countries in Africa have established nuclear energy and radiation facilities for research and applications in many fields, including Agriculture, Medicine, Security, Industry, etc. There is now a new Nuclear power renaissance in Africa. However, in order to derive the full benefits of nuclear energy and radiation technologies, certain protective measures must be established and used correctly Radiation Protection. Radiation Protection in Africa .. At various stages of development, but generally: While the use of ionizing radiation is advancing in many countries in Africa, this is not accompanied by a corresponding effort to ensure radiation protection Constraints: Inadequacies in government support e.g. legislation, training and education; radiation protection infrastructures; Lack of radiation protection professionalism e.g. network and cooperation among RP Professionals and between them and other stakeholders; etc. Some of the pressing needs Strengthening RP infrastructures in Africa; Establishing effective and sustainable cooperation and networks among RP professionals (flow of RP information); Interacting with other stakeholders (governmental

  10. Developing programs for african families, by african families

    DEFF Research Database (Denmark)

    Halliday, Jennifer A; Green, Julie; Mellor, David;

    2013-01-01

    Obesity is an emerging problem for African migrants in Australia, but few prevention programs incorporate their cultural beliefs and values. This study reports on the application of community capacity-building and empowerment principles in 4 workshops with Sudanese families in Australia. Workshop...... effects of physical activity and nutrition to improve health within communities while reducing intergenerational and gender role family conflicts.......Obesity is an emerging problem for African migrants in Australia, but few prevention programs incorporate their cultural beliefs and values. This study reports on the application of community capacity-building and empowerment principles in 4 workshops with Sudanese families in Australia. Workshop...

  11. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

    Jorem, Kaja Tvedten; Jeppesen, Søren; Hansen, Michael W.

    latter suggests that profound improvements in African business performance are indeed under way: with the private sector playing a more important role as an engine of growth, with the rise of a capable African entrepreneurial class, and with the emergence of dynamic and competitive African enterprises......In light of recent enthusiasm over the African private sector, this paper reviews the existing empirical literature on successful African enterprises and proposes an analytical framework for understanding African firm success. Overall, it is argued that we need to develop an understanding of....... The paper proceeds to review the limited research on factors shaping the performance of African enterprises. It is observed that particularly the strategic component is often overlooked as is the role of internal capabilities and resources of African enterprises. Based on this identification of voids...

  12. African N Assessment

    Science.gov (United States)

    Bekunda, M.; Galford, G. L.; Hickman, J. E.; Palm, C.

    2011-12-01

    Africa's smallholder agricultural systems face unique challenges in planning for reducing poverty, concurrent with adaptation and mitigation to climate change. At continental level, policy seeks to promote a uniquely African Green Revolution to increase crop yields and food production, and improve local livelihoods. However, the consequences on the environment and climate are not clear; these pro-economic development measures should be linked to climate change adaptation and mitigation measures, and research is required to help achieve these policy proposals by identifying options, and testing impacts. In particular, increased nitrogen (N) inputs are essential for increasing food production in Africa, but are accompanied by inevitable increases in losses to the environment. These losses appear to be low at input levels promoted in agricultural development programs, while the increased N inputs both increase current food production and appear to reduce the vulnerability of food production to changes in climate. We present field and remote sensing evidence from Malawi that subsidizing improved seed and fertilizers increases resilience to drought without adding excess N to the environment. In Kenya, field research identified thresholds in N2O losses, where emissions are very low at fertilization rates of less than 200 kg ha-1. Village-scale models have identified potential inefficiencies in the food production process where the largest losses of reactive N occur, and which could be targeted to reduce the amount of N released to the environment. We further review some on-going research activities and progress in Africa that compare different methods of managing resources that target resilience in food production and adaptation to climate change, using nutrient N as an indicator, while evaluating the effects of these resource management practices on ecosystems and the environment.

  13. Hypoxia tolerance of two centrarchid sunfishes and an introduced cichlid from karstic Everglades wetlands of southern Florida, U.S.A.

    Science.gov (United States)

    Schofield, P.J.; Loftus, W.F.; Brown, M.E.

    2007-01-01

    In this study, the hypoxia tolerance of three Everglades fishes, two native centrarchids (Lepomis gulosus and Lepomis marginatus) and a recently introduced cichlid (Hemichromis letourneuxi), were documented. Aquatic surface respiration (ASR) thresholds were lowest for H. letourneuxi, followed by L. gulosus, then L. marginatus. The ASR thresholds for L. marginatus were within ranges reported for small, freshwater tropical fishes, while those for L. gulosus were similar to swamp-adapted fishes. For H. letourneuxi, ASR thresholds were some of the lowest reported. All three species showed excellent tolerance of low dissolved oxygen levels when allowed access to the surface. When denied surface access, L. marginatus lost equilibrium at a higher oxygen tension than the other species. Overall, although all species easily tolerated hypoxia, H. letourneuxi appeared to be best equipped to deal with hypoxia, followed by L. gulosus, then L. marginatus. Hemichromis letourneuxi also exhibited more aggressive behaviours than the centrarchids. These results suggest that hypoxia is not likely to prevent H. letourneuxi from exploiting the seasonally inundated wetlands of south Florida while expanding its range there.

  14. Chronic playback of boat noise does not impact hatching success or post-hatching larval growth and survival in a cichlid fish

    Directory of Open Access Journals (Sweden)

    Rick Bruintjes

    2014-09-01

    Full Text Available Anthropogenic (man-made noise has been shown to have a negative impact on the behaviour and physiology of a range of terrestrial and aquatic animals. However, direct assessments of fitness consequences are rare. Here we examine the effect of additional noise on early life stages in the model cichlid fish, Neolamprologus pulcher. Many fishes use and produce sounds, they are crucial elements of aquatic ecosystems, and there is mounting evidence that they are vulnerable to anthropogenic noise; adult N. pulcher have recently been shown to change key behaviours during playback of motor boat noise. Using a split-brood design to eliminate potential genetic effects, we exposed half of the eggs and fry from each clutch to four weeks of playbacks of noise originally recorded from small motor boats with the other half acting as a control (receiving no noise playback. There was no significant effect of additional noise on hatching success or fry survival, length or weight at the end of the exposure period. Although care should be taken not to generalize these findings on a single species from a laboratory study, our data suggest that moderate noise increases do not necessarily have direct negative impacts on early-life survival and growth. Further studies on a range of species in natural conditions are urgently needed to inform conservation efforts and policy decisions about the consequences of anthropogenic noise.

  15. Same school, different conduct: rates of multiple paternity vary within a mixed-species breeding school of semi-pelagic cichlid fish (Cyprichromis spp.).

    Science.gov (United States)

    Anderson, Caleb; Werdenig, Alexandra; Koblmüller, Stephan; Sefc, Kristina M

    2016-01-01

    Mating system variability is known to exist between and within species, often due to environmental influences. An open question is whether, vice versa, similar environmental conditions entail congruent mating behavior, for example in terms of multiple paternity, in species or populations sharing largely comparable breeding modes. This study employed microsatellite markers to investigate the incidence of multiple paternity in Cyprichromis coloratus and Cyprichromis leptosoma, two sympatric, closely related, mouthbrooding Lake Tanganyika cichlids with similar ecological and behavioral characteristics including the formation of open-water schools. Mouthbrooding females of both species were collected from the same mixed-species breeding school at the same time, minimizing environmental variation during courtship and mating. In C. coloratus, four of 12 broods had more than one sire, with a mean of 1.33 reconstructed sires per brood. C. leptosoma exhibited multiple paternity in 18 of 22 broods, with a mean of 2.59 or 2.86 reconstructed sires per brood according to the programs gerud and colony, respectively. In addition, two broods were found to contain offspring transplanted from another brood. There was no significant difference in brood size between species, but mean sire number did differ significantly. Hence, substantial similarity in reproductive behavior along with shared environmental conditions during courtship and spawning did not lead to equal rates of polyandry or sneaking in the two species. PMID:26811772

  16. Comparative support for the expensive tissue hypothesis: Big brains are correlated with smaller gut and greater parental investment in Lake Tanganyika cichlids.

    Science.gov (United States)

    Tsuboi, Masahito; Husby, Arild; Kotrschal, Alexander; Hayward, Alexander; Buechel, Séverine D; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas

    2015-01-01

    The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the energetic requirements of encephalization are suggested to impose considerable constraints on brain size evolution. Three main hypotheses concerning how energetic constraints might affect brain evolution predict covariation between brain investment and (1) investment into other costly tissues, (2) overall metabolic rate, and (3) reproductive investment. To date, these hypotheses have mainly been tested in homeothermic animals and the existing data are inconclusive. However, there are good reasons to believe that energetic limitations might play a role in large-scale patterns of brain size evolution also in ectothermic vertebrates. Here, we test these hypotheses in a group of ectothermic vertebrates, the Lake Tanganyika cichlid fishes. After controlling for the effect of shared ancestry and confounding ecological variables, we find a negative association between brain size and gut size. Furthermore, we find that the evolution of a larger brain is accompanied by increased reproductive investment into egg size and parental care. Our results indicate that the energetic costs of encephalization may be an important general factor involved in the evolution of brain size also in ectothermic vertebrates. PMID:25346264

  17. Untangling the evolutionary history of a highly polymorphic species: introgressive hybridization and high genetic structure in the desert cichlid fish Herichtys minckleyi.

    Science.gov (United States)

    Magalhaes, Isabel S; Ornelas-Garcıa, Claudia Patricia; Leal-Cardin, Mariana; Ramírez, Tania; Barluenga, Marta

    2015-09-01

    Understanding the origin of biodiversity requires knowledge on the evolutionary processes that drive divergence and speciation, as well as on the processes constraining it. Intraspecific polymorphisms can provide insight into the mechanisms that generate and maintain phenotypic, behavioural and life history diversification, and can help us understand not only the processes that lead to speciation but also the processes that prevent local fixation of morphs. The 'desert cichlid' Herichtys minckleyi is a highly polymorphic species endemic to a biodiversity hotspot in northern Mexico, the Cuatro Ciénegas valley. This species is polymorphic in body shape and trophic apparatus, and eco-morphotypes coexist in small spring-fed lagoons across the valley. We investigated the genetic structure of these polymorphisms and their phylogeographic history by analysing the entire control region of the mitochondrial DNA and 10 nuclear microsatellite markers in several populations from different sites and morphs. We found two very divergent mitochondrial lineages that most likely predate the closing of the valley and are not associated with morphotypes or sites. One of these lineages is also found in the sister species Herichthys cyanoguttatus. Data from neutral microsatellite markers suggest that most lagoons or drainages constitute their own genetic cluster with sympatric eco-morphotypes forming panmictic populations. Alternative mechanisms such as phenotypic plasticity and a few loci controlled traits provide possible explanations for the sympatric coexistence of discrete nonoverlapping eco-morphotypes with apparent lack of barriers to gene flow within multiple lagoons and drainages. PMID:26175313

  18. The transmission of African culture to children

    OpenAIRE

    Michele Tanon Lora

    2014-01-01

    African ancient traditions suffered a major historical change as a result of colonization. Several decades after decolonization and access to independence, what is the situation and place of the African culture in Africa and outside Africa? Does African culture perpetuate effectively today? What are the obstacles to the transmission of African culture to our children? What are the beliefs or elements that have influenced the transmission of our culture after the period of independence? Roughl...

  19. Translating Culture: Contemporary African American Poetry

    OpenAIRE

    Kristina Kočan Šalamon

    2015-01-01

    The paper interrogates cultural specifics of contemporary African American poetry and exhibits translation problems when translating this poetic work. African American writers have always included much of their cultural heritage in their writing and this is immediately noticed by a translator. The cultural elements, such as African American cuisine, attire and style in general, as well as spiritual and religious practices, often play a significant role for African American poets who are procl...

  20. Urbanism beyond Architecture : African cities as Infrastructure

    OpenAIRE

    Rao, Vyjayanthi; De Boeck, Filip; Simone, Abdou Maliq

    2009-01-01

    About African Cities Reader(A creation of the African Centre for Cities & Chimurenga Magazine ) In many senses African cities are amongst the most generative and vibrant places on the planet. Yet, we know next to nothing about what goes on in the places. Not that there is any shortage of caricature, hyperbole or opinion about what makes African cities such quintessential spaces of dystopia and atrophy. We believe that a range of interventions that seek to engage the shape-shifting essenc...

  1. MORE CHINESE CARS ON AFRICAN ROADS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China drives into the African vehicle market and meets the challenges head on with some advantages of its own High-quality but inexpensive Chinese automobiles have gradually won the confidence of the African market and are becoming a bright new link in Sino-African economic ties. On September 4, a total of 400 Polarsun minibuses, made in Shenyang, capital of northeast

  2. Engaging African Americans in Smoking Cessation Programs

    Science.gov (United States)

    Wallen, Jacqueline; Randolph, Suzanne; Carter-Pokras, Olivia; Feldman, Robert; Kanamori-Nishimura, Mariano

    2014-01-01

    Background: African Americans are disproportionately exposed to and targeted by prosmoking advertisements, particularly menthol cigarette ads. Though African Americans begin smoking later than whites, they are less likely to quit smoking than whites. Purpose: This study was designed to explore African American smoking cessation attitudes,…

  3. How student teachers understand African philosophy

    Directory of Open Access Journals (Sweden)

    Matsephe M. Letseka

    2012-10-01

    Full Text Available The question ‘What constitutes African philosophy?’ was first raised with the publication of Placide Tempels’s seminal work Bantu philosophy in 1959. Tempels’s book inevitably elicited considerable critical response from African philosophers, which culminated in a wide range of publications such as Wiredu’s (1980 Philosophy and an African culture, Hountondji’s (1983 African philosophy: Myth and reality, Oruka’s (1990 Sage philosophy: Indigenous thinkers and modern debate on African philosophy, Shutte’s (1993 Philosophy for Africa, Masolo’s (1994 African philosophy in search of identity and Gyekye’s (1995 An essay of African philosophical thought: The Akan conceptual scheme. It has been over 60 years since the publication of Temples’s book and there continues to be serious debate about African philosophy. This article sought to contribute to the debate on the various conceptions of African philosophy, but with a focus on the challenges of teaching African philosophy to Philosophy of Education students at an open distance learning institution in South Africa. This article discussed the tendency amongst undergraduate Philosophy of Education students to conflate and reduce African philosophy to African cultures and traditions, and to the notion of ubuntu, and sought to understand the reasons for students’ inclination to treat African philosophy in this way. It examined students’ background knowledge of African philosophy, their critical thinking skills and whether their official study materials are selected and packaged in a manner that, in fact, adds to the challenges they face. Finally, the article explored the ways in which Philosophy of Education lecturers can adapt their pedagogy to provide students with a better understanding of African philosophy.

  4. African aerosol and trace-gas emissions from the Central-African Bujumbura station.

    Science.gov (United States)

    Gielen, Clio; Van Roozendael, Michel; Hendrick, Francois; Pinardi, Gaia; De Smet, Isabelle; Fayt, Caroline; Hermans, Christian; Ndenzako, Eugene; Nzohabonayo, Pierre; Akimana, Rachel

    2015-04-01

    We present aerosol and trace-gas retrievals from the new Central-African measurement site of Bujumbura, where a new MAX-DOAS instrument and cimel sun photometer have been operational since late 2013. This is the first time that MAX-DOAS measurements are performed in Central Africa, which are critical to resolve the large uncertainties of satellite observations of trace gases and aerosols over this area. The Bujumbura region is a source of strong biogenic compounds and biomass burning products, and invaluable to study the export of African emissions to the Indian ocean. Using the bePRO radiative transfer tool, we retrieve aerosol optical depths (AODs) and vertical extinction profiles for aerosols and trace gases such as NO2 and HCHO. The AOD retrievals are compared to the co-located AERONET sun photometer measurements and further analysed to investigate seasonal and diurnal cycles in the observed variability or to detect biomass-burning events.For the trace gases NO2 and HCHO, the ground-based MAX-DOAS vertical columns and profiles are used for tropospheric trace-gas validation of the GOME-2 and OMI satellites. We further discuss the representativity of the site regarding satelitte comparisons and modelling efforts, given its specific orography.

  5. South African Association of Physicists in Medicine and Biology: 25. Anniversary Congress, 18-22 Mar 1985, Cape Town

    International Nuclear Information System (INIS)

    The twenty-fifth anniversary congress of the South African Association of Physicists in Medicine and Biology was held from 18-22 March 1985 in Cape Town. The tremendous growth of nuclear energy and radiation technology in South Africa led to an increasing need for biophysicists, especially health physicists, for the application of radioisotopes and radiation as well as nuclear power, including the uranium industry. Papers delivered on the conference covered subjects like medical physics, radiotherapy, radiopharmaceuticals, radiation protection, the calibration of radiation monitors, radiation detectors, radiation doses and dosimetry

  6. Ninth national conference of the South African Section of the PRI

    International Nuclear Information System (INIS)

    This publication contains the papers of the ninth national conference of the South African Section of the Plastics and Rubber Institute held at Johannesburg on the 22nd and 23rd October 1987. The papers cover the different applications of polymers and two seminars particularly discuss the chemical radiation effects on polymers

  7. African women, literature, language and culture

    OpenAIRE

    Rosamond S. King

    2014-01-01

    This essay will link African women’s writing to culture, including literary culture and the politics of literature. It describes how African women’s literature can act as a mirror, reflecting African cultures to Africans, and how it can serve as a window and a door, revealing African cultures to those outside of them in whole or in part. It ends with a description of “communal agency,” an example of how scholarly writing can act as a door for both those who are and are not a part of a literat...

  8. East African odontopygid millipedes 1

    DEFF Research Database (Denmark)

    Frederiksen, Sara B.; Enghoff, Henrik

    2012-01-01

    Five new species of the endemic East African genus Xystopyge are described: X. pelecys, X. frontieri, X. proplicatus, X. biacanthus, and X. zanzibarensis. Three are from the Eastern Arc Mountains, Tanzania, two are from the Usambara Mtns. and one is from the Uluguru Mtns. One further species is...

  9. Wellness among African American Counselors

    Science.gov (United States)

    Day-Vines, Norma L.; Holcomb-McCoy, Cheryl

    2007-01-01

    Although there are various definitions of wellness, few conceptual definitions have addressed the contextual dimensions of wellness relative to African American counselors. The authors present an overview of generic models of wellness, discuss factors that both inhibit and promote wellness, offer some culture-specific models of wellness, and…

  10. Quo vadis South African universities?

    OpenAIRE

    Johann RE lutjeharms

    2007-01-01

    The Economist has recently identified some specific factors that explain why European universities are not competing adequately with their American counterparts. These factors are used here to evaluate South African government policy for universities. It is demonstrated that this current policy is directly contrary to what is now internationally considered best for universities in a knowledge economy.

  11. Vitamin D and African Americans

    Science.gov (United States)

    Vitamin D insufficiency is more prevalent among African Americans than other Americans and, in North America, most young, healthy blacks do not achieve optimal 25-hydroxyvitamin D [25(OH)D] concentrations at any time of the year. This is primarily due to the fact that pigmentation reduces vitamin D...

  12. African Easterly Waves and convective activity in wet and dry sequences of the West African Monsoon

    Energy Technology Data Exchange (ETDEWEB)

    Lavaysse, Christophe; Laurent, Henri; Lebel, Thierry [LTHE, BP 53, Grenoble Cedex 9 (France); Diedhiou, Arona [IRD-Niger, BP 11416, Niamey (Niger)

    2006-08-15

    Janicot and Sultan (Geophys Res Lett 28(3):523-526, 2001) and Sultan et al. (J Clim 16(21):3389-3406, 2003) showed evidence of an intraseasonal signal of Sahelian rainfall corresponding to wet and dry sequences of the West African Monsoon. Using NCEP/NCAR reanalysis, NOAA outgoing longwave radiation (OLR) and observed daily rainfall over West Africa from 1968 to 1990, this paper investigates the variability of 3 to 5-day African Easterly Waves (AEWs), convection and their relationship with rainfall in these wet and dry sequences. The mean daily value rainfall during wet sequences is twice the mean value during dry sequences but the number of dry or wet sequences per year is not correlated with the annual rainfall. Wet sequences account for 39% of the annual accumulated rainfall while dry sequences account for 22%. The number of 3 to 5-day AEWs increases during wet years in wet sequences and the activity tends to be larger during wet years in both wet and dry sequences. These AEWs explain 40% of the accumulated rainfall during wet sequences whereas they contribute to 26% of the accumulated rainfall observed during dry sequences. Generally, they contribute to the increase of rainfall during these sequences. Mean convection is stronger and there are twice as many low OLR days (<225W/m{sup 2}) during wet than dry sequences. The mean rainfall for days with high convective activity (convective days) is also twice as great during wet sequences. Rainfall that occurs during days without low OLR (weak convection with warm cloud tops or isolated deep convection) contributes to 69% of the total rainfall during dry sequences and 45% during wet sequences. A composite study was performed from day D{sub 0}-10 to day D{sub 0}+10 in each sequence. Wet (dry) sequences of the African monsoon start with a decrease (slight increase) of the negative meridional Ertel Potential Vorticity (PV) gradient at 700 hPa, associated with an increase (decrease) of the spectral density of AEWs

  13. Dietary habits of juveniles of the Mayan cichlid, Cichlasoma urophthalmus, in mangrove ponds of an offshore islet in Belize, Central America

    Directory of Open Access Journals (Sweden)

    Amandine Vaslet

    2012-09-01

    Full Text Available Foraging habitats of juveniles of the Mayan cichlid, Cichlasoma urophthalmus (Günther, 1862, were investigated in two mangrove ponds located in Twin Cays offshore islet in Belize: Sink Hole pond (SH and Hidden Lake pond (HL. Sink Hole pond is a semiclosed body of water, whereas Hidden Lake pond is connected by a channel to adjacent seagrass beds that surround the islet. Gut contents of 21 juvenile C. urophthalmus (9.8-13.2 cm total length were analyzed, and five prey taxa were identified. In both mangrove ponds, C. urophthalmus were opportunistic carnivores and consumed primarily crustaceans. Plant material and detritus present in gut contents were most likely ingested incidentally when the fish foraged on small invertebrates. Carbon isotopic values of fish specimens from the two ponds were similar (mean ± SD of -19.2 ± 0.4‰ in SH and -19.4 ± 0.4‰ in HL, and were close to those of mangrove prey (mean ± SD = -20.2 ± 1.5‰, suggesting that this fish species forages in this habitat. Mixing models showed a higher contribution of mangrove food sources to the fish diet than seagrass food sources. This study reveals that young Mayan cichlids, inhabiting two Belize mangrove ponds, are generalists and opportunistic carnivores that forage on mangrove food sources and do not appear to move to adjacent seagrass beds to complement their diets. Understanding trophic linkages between aquatic consumers and food resources may contribute to better management of threatened coastal ecosystems.Habitats de alimentação de juvenis do ciclídeo-maia, Cichlasoma urophthalmus (Günther, 1862, foram investigados em duas lagoas de mangue localizadas nas ilhas Twin Cays em alto mar em Belize: Sink Hole Lake (SH e Hidden Lake (HL. Sink Hole é um corpo d'água parcialmente isolado, enquanto Hidden Lake é ligada por um canal com bancos de sargaços que cercam a ilhota. O conteúdo estomacal de 21 juvenil de C. urophthalmus (9,8-13,2 cm de comprimento total foram

  14. Genetic evidence for prevalence of alloparental care in a socially monogamous biparental cichlid fish, Perissodus microlepis, from Lake Tanganyika supports the "selfish shepherd effect" hypothesis.

    Science.gov (United States)

    Lee, Hyuk Je; Heim, Valentin; Meyer, Axel

    2016-05-01

    Alloparental care - care for unrelated young - is rare in animals, and its ecological or evolutionary advantages or, alternative maladaptive nature, remain unclear. We investigate alloparental care in the socially monogamous cichlid fish Perissodus microlepis from Lake Tanganyika that exhibits bi-parental care. In a genetic parentage analysis, we discovered a surprisingly high percentage of alloparental care represented by brood mixing, extra-pair paternity and extra-pair maternity in all broods that we investigated. The percentage of nondescendant juveniles of other parents, i.e., brood mixing, ranged from 5% to 57% (mean = 28%). The distribution of genetic parentage also suggests that this socially monogamous species has, in fact, polygamous mating system. The prevalence of genetically mixed broods can be best explained by two, not mutually exclusive hypotheses on farming-out and fostering behaviors. In the majority of broods, the sizes of the parents' own (descendant) offspring were significantly larger than those of the adopted (nondescendant) juveniles, supporting the 'selfish shepherd effect' hypothesis, i.e., that foster parents preferentially accept unrelated "smaller or not larger" young since this would tend to lower the predation risks for their own larger offspring. There was also a tendency for larger parents particularly mothers, more so than smaller parents, to care predominantly for their own offspring. Larger parents might be better at defending against cuckoldry and having foreign young dumped into their broods through farming-out behavior. This result might argue for maladaptive effects of allopatric care for the foster parents that only larger and possibly more experienced pairs can guard against. It needs to be determined why, apparently, the ability to recognize one's own young has not evolved in this species. PMID:27217943

  15. Serotonergic outcome, stress and sexual steroid hormones, and growth in a South American cichlid fish fed with an L-tryptophan enriched diet.

    Science.gov (United States)

    Morandini, Leonel; Ramallo, Martín Roberto; Moreira, Renata Guimarães; Höcht, Christian; Somoza, Gustavo Manuel; Silva, Ana; Pandolfi, Matías

    2015-11-01

    Reared animals for edible or ornamental purposes are frequently exposed to high aggression and stressful situations. These factors generally arise from conspecifics in densely breeding conditions. In vertebrates, serotonin (5-HT) has been postulated as a key neuromodulator and neurotransmitter involved in aggression and stress. The essential amino acid L-tryptophan (trp) is crucial for the synthesis of 5-HT, and so, leaves a gateway for indirectly augmenting brain 5-HT levels by means of a trp-enriched diet. The cichlid fish Cichlasoma dimerus, locally known as chanchita, is an autochthonous, potentially ornamental species and a fruitful laboratory model which behavior and reproduction has been studied over the last 15years. It presents complex social hierarchies, and great asymmetries between subordinate and dominant animals in respect to aggression, stress, and reproductive chance. The first aim of this work was to perform a morphological description of chanchita's brain serotonergic system, in both males and females. Then, we evaluated the effects of a trp-supplemented diet, given during 4weeks, on brain serotonergic activity, stress and sexual steroid hormones, and growth in isolated specimens. Results showed that chanchita's brain serotonergic system is composed of several populations of neurons located in three main areas: pretectum, hypothalamus and raphe, with no clear differences between males and females at a morphological level. Animals fed with trp-enriched diets exhibited higher forebrain serotonergic activity and a significant reduction in their relative cortisol levels, with no effects on sexual steroid plasma levels or growth parameters. Thus, this study points to food trp enrichment as a "neurodietary'' method for elevating brain serotonergic activity and decreasing stress, without affecting growth or sex steroid hormone levels. PMID:26449161

  16. A test of genetic association among male nuptial coloration,female mating preference, and male aggression bias within a polymorphic population of cichlid fish

    Institute of Scientific and Technical Information of China (English)

    Inke van der SLUIJS; Peter D.DIJKSTRA; Charlotte M.LINDEYER; Bertanne VISSER; Alan M.SMITH; Ton G.G.GROOTHUIS; Jacques J.M.van ALPHEN

    2013-01-01

    Both inter-and intrasexual selection have been implicated in the origin and maintenance of species-rich taxa with diverse sexual traits.Simultaneous disruptive selection by female mate choice and male-male competition can,in theory,lead to speciation without geographical isolation if both act on the same male trait.Female mate choice can generate discontinuities in gene flow,while male-male competition can generate negative frequency-dependent selection stabilizing the male trait polymorphism.Speciation may be facilitated when mating preference and/or aggression bias are physically linked to the trait they operate on.We tested for genetic associations among female mating preference,male aggression bias and male coloration in the Lake Victoria cichlid Pundamilia.We crossed females from a phenotypically variable population with males from both extreme ends of the phenotype distribution in the same population (blue or red).Male offspring of a red sire were significantly redder than males of a blue sire,indicating that intra-population variation in male coloration is heritable.We tested mating preferences of female offspring and aggression biases of male offspring using binary choice tests.There was no evidence for associations at the family level between female mating preferences and coloration of sires,but dam identity had a significant effect on female mate preference.Sons of the red sire directed significantly more aggression to red than blue males,whereas sons of the blue sire did not show any bias.There was a positive correlation among individuals between male aggression bias and body coloration,possibly due to pleiotropy or physical linkage,which could facilitate the maintenance of color polymorphism.

  17. Disparities in colorectal cancer in African-Americans vs Whites: Before and after diagnosis

    Institute of Scientific and Technical Information of China (English)

    Anastasios Dimou; Kostas N Syrigos; Muhammad Wasif Saif

    2009-01-01

    There are differences between African-American and white patients with colorectal cancer, concerning their characteristics before and after diagnosis. Whites are more likely to adhere to screening guidelines. This is also the case among people with positive family history. Colorectal cancer is more frequent in Blacks. Studies have shown that that since 1985, colon cancer rates have dipped 20% to 25% for Whites, while rates have gone up for African-American men and stayed the same for African-American women. Overall, African-Americans are 38% to 43% more likely to die from colon cancer than are Whites. Furthermore, it seems that there is an African-American predominance in right-sited tumors. African Americans tend to be diagnosed at a later stage, to suffer from better differentiated tumors, and to have worse prognosis when compared with Whites. Moreover, less black patients receive adjuvant chemotherapy for resectable colorectal cancer or radiation therapy for rectal cancer. Caucasians seem to respond better to standard chemotherapy regimens than African- Americans. Concerning toxicity, it appears that patients of African-American descent are more likely to develop 5-FU toxicity than Whites, possibly because of their different dihydropyridine dehydrogenase status. Last but not least, screening surveillance seems to be higher among white than among black long-term colorectal cancer survivors. Socioeconomic and educational status account for most of these differences whereas little evidence exists for a genetic contribution in racial disparity. Understanding the nature of racial differences in colorectal cancer allows tailoring of screening and treatment interventions.

  18. Field determination of biomass burning emission ratios and factors via open-path FTIR spectroscopy and fire radiative power assessment: headfire, backfire and residual smouldering combustion in African savannahs

    Directory of Open Access Journals (Sweden)

    M. J. Wooster

    2011-11-01

    Full Text Available Biomass burning emissions factors are vital to quantifying trace gas release from vegetation fires. Here we evaluate emissions factors for a series of savannah fires in Kruger National Park (KNP, South Africa using ground-based open path Fourier transform infrared (FTIR spectroscopy and an IR source separated by 150–250 m distance. Molecular abundances along the extended open path are retrieved using a spectral forward model coupled to a non-linear least squares fitting approach. We demonstrate derivation of trace gas column amounts for horizontal paths transecting the width of the advected plume, and find for example that CO mixing ratio changes of ~0.01 μmol mol−1 [10 ppbv] can be detected across the relatively long optical paths used here. Though FTIR spectroscopy can detect dozens of different chemical species present in vegetation fire smoke, we focus our analysis on five key combustion products released preferentially during the pyrolysis (CH2O, flaming (CO2 and smoldering (CO, CH4, NH3 processes. We demonstrate that well constrained emissions ratios for these gases to both CO2 and CO can be derived for the backfire, headfire and residual smouldering combustion (RSC stages of these savannah fires, from which stage-specific emission factors can then be calculated. Headfires and backfires often show similar emission ratios and emission factors, but those of the RSC stage can differ substantially. The timing of each fire stage was identified via airborne optical and thermal IR imagery and ground-observer reports, with the airborne IR imagery also used to derive estimates of fire radiative energy (FRE, allowing the relative amount of fuel burned in each stage to be calculated and "fire averaged" emission ratios and emission factors to be determined. These "fire averaged" metrics are dominated by the headfire contribution, since the FRE data indicate that the vast majority

  19. Field determination of biomass burning emission ratios and factors via open-path FTIR spectroscopy and fire radiative power assessment: headfire, backfire and residual smouldering combustion in African savannahs

    Directory of Open Access Journals (Sweden)

    M. J. Wooster

    2011-02-01

    Full Text Available Biomass burning emissions factors are vital to quantifying trace gases releases from vegetation fires. Here we evaluate emissions factors for a series of savannah fires in Kruger National Park (KNP, South Africa using ground-based open path Fourier transform infrared (FTIR spectroscopy and an infrared lamp separated by 150–250 m distance. Molecular abundances along the extended open path are retrieved using a spectral forward model coupled to a non-linear least squares fitting approach. We demonstrate derivation of trace gas column amounts for horizontal paths transecting the width of the advected plume, and find, for example, that CO mixing ratio changes of ~0.001 μmol mol−1 (~10 ppbv can be detected across the relatively long optical paths used here. We focus analysis on five key compounds whose production is preferential during the pyrolysis (CH2O, flaming (CO2 and smoldering (CO, CH4, NH3 fire phases. We demonstrate that well constrained emissions ratios for these gases to both CO2 and CO can be derived for the backfire, headfire and residual smouldering combustion stages of these savannah fires, from which stage-specific emission factors can then be calculated. Headfires and backfires in general show similar emission ratios and emission factors, but those of the residual smouldering combustion stage can differ substantially (e.g., ERCH4/CO2 up to ~7 times higher than for the flaming stages. The timing of each fire stage was identified via airborne optical and thermal IR imagery and ground-observer reports, with the airborne IR imagery also used to derive estimates of fire radiative energy, thus allowing the relative amount of fuel burned in each stage to be calculated and the "fire averaged" emission ratios and emission factors to be determined. The derived "fire averaged" emission ratios are dominated by the headfire contribution, since

  20. The UCAR Africa Initiative: Enabling African Solutions to African Needs

    Science.gov (United States)

    Pandya, R.; Bruintjes, R.; Foote, B.; Heck, S.; Hermann, S.; Hoswell, L.; Konate, M.; Kucera, P.; Laing, A.; Lamptey, B.; Moncrieff, M.; Ramamurthy, M.; Roberts, R.; Spangler, T.; Traoré, A.; Yoksas, T.; Warner, T.

    2007-12-01

    The University Corporation for Atmospheric Research (UCAR) Africa Initiative (AI) is a coordinated effort aimed at building sustainable partnerships between UCAR and African institutions in order to pursue research and applications for the benefit of the African people. The initiative is based on four fundamental operating principles, concisely summarized by the overall philosophy of enabling African solutions to African needs. The four principles are: • Collaborate with African institutions • Focus on institutional capacity building and research support • Explore science research themes critical to Africa and important for the world • Leverage the research infrastructure in UCAR to add value These principles are realized in a set of pilot activities, chosen for their high probability of short-term results and ability to set the stage for longer-term collaboration. The three pilot activities are listed below. 1. A modest radar network and data-distribution system in Mali and Burkina Faso, including a data-sharing MOU between the Mail and Burkina Faso Weather Services. 2. A partnership among UCAR, the Ghana Meteorological Agency, and the Ghana university community to develop an operational Weather Research and Forecasting (WRF) model for West Africa. The output is used by researchers and operational forecasters in Africa. Model output is also part of a demonstration project that aims to allow humanitarian agencies to share geo-referenced information in Africa via a web portal. 3. A workshop in Ouagadougou, Burkina Faso from April 2-6, 2007, with the theme Improving Lives by Understanding Weather. The workshop, co-organized with Programme SAAGA and the Commité Permanent Inter-Etats de Lutte Contre la Sécheresse dans le Sahel (CILSS), included over 80 participants from 18 countries, and produced a set of recommendations for continued collaboration. Our presentation will provide an update of these pilot activities and point to future directions. Recognizing

  1. The African Financial Development Gap

    OpenAIRE

    Allen, Franklin; Carletti, Elena; Cull, Robert; Qian, Jun; Senbet, Lemma

    2010-01-01

    Economic growth in Africa has long been disappointing. We document that the financial sectors of most sub-Saharan African countries remain significantly underdeveloped by the standards of other developing countries. We examine the factors that are associated with financial development in Africa and compare them with those in other developing countries. Population density appears to be considerably more important for banking sector development in Africa than elsewhere. Given the high costs of ...

  2. Recent growth in African cassava

    OpenAIRE

    Nweke, Felix; Haggblade, Steven; Zulu, Ballard

    2004-01-01

    According to the authors, "Cassava serves as a staple food for 200 million Africans, second only to maize in its calorie contribution. In response to a series of devastating attacks by cassava diseases and pests over the past several decades, the International Institute of Tropical Agriculture (IITA) and several national agricultural research services have launched successful cassava research programs... " This brief describes some of the programs, their impact and the drivers of change. It c...

  3. Financial Liberalization: The African Experience

    OpenAIRE

    Reinhart, Carmen; Tokatlidis, Ioannis

    2000-01-01

    Almost a decade after their initiation, financial reforms appear to have had little effect on the economies of Sub-Sahara Africa. Whether the blame is to fall on their initial design itself, or on the partial nature of their implementation, liberalization policies have not mobilized savings, deepened intermediation or raised investment. Yet, Africa needs properly functioning financial markets for a more efficient allocation of resources for growth and risk diversification. How can African go...

  4. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

    Jorem, Kaja Tvedten; Hansen, Michael Wendelboe; Jeppesen, Søren

    2014-01-01

    enterprises, observing that while much research is focusing on the role of the African business environments for enterprise development, much less attention has been devoted to the role of firm-specific capabilities, strategies and management. The paper concludes by advocating a contingency approach to...... research on African enterprise development that emphasizes the interplay between firm-specific factors and the specificities of the African business environment. Originality/value: The paper provides a comprehensive literature review on African enterprise development and presents a novel framework for......Purpose: In light of recent enthusiasm over African private sector development, the purpose of this paper is to review the business literature on African enterprise development with a view of identifying lacunas in the literature and of developing an analytical framework that may guide future...

  5. Ideology and the possibility of African political theory: African socialism and “ubuntu” compared

    OpenAIRE

    Gil, Manuel

    2011-01-01

    This article explores the lack of investigation into African political theory in the postcolonial period. After discussing the epistemological problems in the study of African political thought, the paper then adopts Michael Freeden’s methodology for the analysis of political ideologies. Through this approach a comparison is made between African Socialism and ubuntu. African Socialism – as developed by Cabral, Nkrumah, Nyerere and Senghor – is defined by its core commitment to freedom from co...

  6. Repeated adaptive divergence of microhabitat specialization in avian feather lice

    OpenAIRE

    Johnson Kevin P; Shreve Scott M; Smith Vincent S

    2012-01-01

    Abstract Background Repeated adaptive radiations are evident when phenotypic divergence occurs within lineages, but this divergence into different forms is convergent when compared across lineages. Classic examples of such repeated adaptive divergence occur in island (for example, Caribbean Anolis lizards) and lake systems (for example, African cichlids). Host-parasite systems in many respects are analogous to island systems, where host species represent isolated islands for parasites whose l...

  7. Ectomycorrhizal symbiosis of tropical African trees

    OpenAIRE

    Bâ, Amadou; Duponnois, Robin; Moyersoen, B.; Diédhiou, A.G.

    2012-01-01

    The diversity, ecology and function of ectomycorrhizal (EM) fungi and ectomycorrhizas (ECMs) on tropical African tree species are reviewed here. While ECMs are the most frequent mycorrhizal type in temperate and boreal forests, they concern an economically and ecologically important minority of plants in African tropical forests. In these African tropical forests, ECMs are found mainly on caesalpionioid legumes, Sarcolaenaceae, Dipterocarpaceae, Asterpeiaceae, Phyllantaceae, Sapotaceae, Papil...

  8. 21st Century South African Science Fiction

    OpenAIRE

    CARAIVAN LUIZA

    2014-01-01

    The paper analyses some aspects of South African science fiction, starting with its beginnings in the 1920s and focusing on some 21st century writings. Thus Lauren Beukes’ novels Moxyland (2008) and Zoo City (2010) are taken into consideration in order to present new trends in South African literature and the way science fiction has been marked by Apartheid. The second South African science fiction writer whose writings are examined is Henrietta Rose-Innes (with her novel Nineveh, published i...

  9. African Music: Source of the Blues

    OpenAIRE

    Bayer, Konrad Sidney

    2010-01-01

    [Abstract] African music is the primary source for the blues. Scholars have supplied ample evidence to support this assertion. However, the African retentions still present in the blues are not immediately apparent. African music and the blues share many similarities, including the predominance of rhythm, the uses of music as social commentary and critique, types of instruments, and musical structure. Slaves brought their culture with them to the New World when they were forcibly taken from t...

  10. Representation of African Heritage in Trinidad Carnival

    OpenAIRE

    三吉, 美加

    2016-01-01

    This paper focuses on the cultural representation of African Trinidadian or African creole in Trinidad Carnival. The Republic of Trinidad and Tobago is the most ethnically and culturally diverse society in the East Caribbean. This diversity comprises of 40 percent of East Indians, 40 percent of Africans, and 20 percent of mixed race such as Chinese, Syrians, Lebanese, and Europeans. In the course of making tourism a national agenda, Carnival has gained commercial values, diversifying particip...

  11. 75 FR 45600 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-08-03

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, August 17, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  12. 75 FR 2844 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-01-19

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, January 26, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  13. 75 FR 14418 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-03-25

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, April 13, 2010, 9:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  14. The State of African Stock Markets

    OpenAIRE

    Mahama, Adnan

    2013-01-01

    The paper looks at the state of African stock markets during and after the global economic crisis of 2008. The research focuses on the market performance of 15 African stock exchanges from 2007-2012. The size and liquidity of stock markets in the African region is discussed in this thesis. In addition, it compares the performances of a few indexes in the emerging and developed markets to that of African indexes. Data is gathered from individual stock markets as well as notable institutions su...

  15. Race, health, and the African Diaspora.

    Science.gov (United States)

    Spigner, Clarence

    Health inequalities exist throughout the African Diaspora and are viewed in this article as largely color-coded. In developed, developing, and undeveloped nations today, "racial" stratification is consistently reflected in an inability to provide adequate health regardless of national policy or ideology. For instance, African Americans experience less than adequate health care very similar to Blacks in Britain, in spite of each nations differing health systems. Latin America's Africana Negra communities experience poorer health similar to Blacks throughout the Caribbean. The African continent itself is arguably the poorest on earth. A common history of racism correlates with health disparities across the African Diaspora. PMID:18364304

  16. Stability versus diversity of the dentition during evolutionary radiation in cyprinine fish.

    Science.gov (United States)

    Pasco-Viel, Emmanuel; Yang, Lei; Veran, Monette; Balter, Vincent; Mayden, Richard L; Laudet, Vincent; Viriot, Laurent

    2014-04-01

    Evolutionary radiations, especially adaptive radiations, have been widely studied but mainly for recent events such as in cichlid fish or Anolis lizards. Here, we investigate the radiation of the subfamily Cyprininae, which includes more than 1300 species and is estimated to have originated from Southeast Asia around 55 Ma. In order to decipher a potential adaptive radiation, within a solid phylogenetic framework, we investigated the trophic apparatus, and especially the pharyngeal dentition, as teeth have proved to be important markers of ecological specialization. We compared two tribes within Cyprininae, Poropuntiini and Labeonini, displaying divergent dental patterns, as well as other characters related to their trophic apparatus. Our results suggest that the anatomy of the trophic apparatus and diet are clearly correlated and this explains the difference in dental patterns observed between these two tribes. Our results illustrate the diversity of mechanisms that account for species diversity in this very diverse clade: diversification of dental characters from an ancestral pattern on the one hand, conservation of a basal synapomorphy leading to ecological specialization on the other hand. By integrating morphological, ecological and phylogenetic analyses, it becomes possible to investigate ancient radiation events that have shaped the present diversity of species. PMID:24523268

  17. Nuclear regulation of South African mines: An industry perspective

    International Nuclear Information System (INIS)

    South African mines have become subject to a rigid and prescriptive system of nuclear regulation that has its roots in the past when South Africa embarked upon a period of nuclear development spanning the full nuclear fuel cycle, and in which the South African gold mining industry once played a major part in the supply of uranium as a low grade by-product. Radiation hazards in the mines are generally very moderate, even in the few gold mines associated with uranium by-product, and to not warrant the type of regulatory attention normally applied to nuclear installations, or even to uranium mines. The continued imposition of strict nuclear regulatory requirements has caused severe financial hardship and threatens the survival of certain mining operations, while seemingly having little or no health benefits to workers or the public. With the development of modern, comprehensive mine health and safety legislation, a more appropriate, effective, and far less costly vehicle for controlling radiation hazards in mines now exists, utilizing the resources of the Mine Health and Safety Inspectorate. This approach is now being proposed, in the drafting of new legislation, as constituting a better alternative to the nuclear regulation of mines. (author)

  18. LGBT African-American Individuals and African-American Same-Sex Couples

    OpenAIRE

    Gates, Gary J.; Kastanis, Angel

    2013-01-01

    An estimated 1,018,700 or 3.7 percent of African-American adults consider themselves lesbian, gay, bisexual or transgender (LGBT) and 34 percent of African-American same-sex couples are raising children. Currently, the estimated 84,000 African-American individuals in same-sex couples tend to live in areas where there are higher proportions of African-Americans. For example, a quarter of African-American same-sex couples live in Georgia, New York, North Carolina, and Maryland. The rep...

  19. The African agent discovered: The recognition and involvement of the African biblical interpreter in Bible translation

    Directory of Open Access Journals (Sweden)

    S V Coertze

    2008-05-01

    Full Text Available This article explores the extent to which the role of the African biblical interpreter is acknowledged in the process of Bible translation, as the Bible and Bible translation form an important part of the establishment of the African church on the continent of Africa. It points out that even though foreign discovery of African agency in Bible translation is evident, indigenous discovery of the same is largely absent. Part of the relevance of this article is for the African church to own and be actively involved in the translation of the Bible into the remaining African languages that are in need of a translation of the Bible.

  20. Radiation dosimetry.

    OpenAIRE

    Cameron, J.

    1991-01-01

    This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists.

  1. Population genetics of African ungulates

    DEFF Research Database (Denmark)

    Lorenzen, Eline

    Molecular genetic techniques were used to gain insights into the evolutionary forces that have shaped the present day diversity of African savannah ungu-lates, which constitute the most species-rich mega faunal assemblage on earth. The studies included in this thesis represent individual species......-specific data sets, which are used to elucidate evolutionary processes of importance to the savannah ungulate community. Patterns of DNA variation were analyzed to assess the genetic signatures of Pleistocene refugia and investigate aspects of speciation, intraspecific structuring, hybridization, and historic...

  2. Environmental sensing by African trypanosomes.

    Science.gov (United States)

    Roditi, Isabel; Schumann, Gabriela; Naguleswaran, Arunasalam

    2016-08-01

    African trypanosomes, which divide their life cycle between mammals and tsetse flies, are confronted with environments that differ widely in temperature, nutrient availability and host responses to infection. In particular, since trypanosomes cannot predict when they will be transmitted between hosts, it is vital for them to be able to sense and adapt to their milieu. Thanks to technical advances, significant progress has been made in understanding how the parasites perceive external stimuli and react to them. There is also a growing awareness that trypanosomes use a variety of mechanisms to exchange information with each other, thereby enhancing their chances of survival. PMID:27131101

  3. Depression, Sociocultural Factors, and African American Women

    Science.gov (United States)

    Hunn, Vanessa Lynn; Craig, Carlton David

    2009-01-01

    The authors discuss depression in African American women from a sociocultural perspective, including aspects of oppression and racism that affect symptom manifestation. The authors highlight John Henryism as a coping mechanism, the history and continuing role of the African American church as a safe haven, and strategies for culturally competent…

  4. Cancer and the African American Experience

    Science.gov (United States)

    The first plenary of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans explores the many factors that lead to inequalities in cancer care outcomes for African Americans.

  5. African Americans in the Early Republic.

    Science.gov (United States)

    Nash, Gary B.

    2000-01-01

    Discusses five topics on African Americans that are essential to studying United States History in the years between 1760 and 1830: (1) African Americans in the Revolutionary War ; (2) the rise of free black communities; (3) early abolitionism; (4) the spread of slavery; and (5) black resistance to slavery. (CMK)

  6. African-American Student Achievement Research Project.

    Science.gov (United States)

    Wagstaff, Mark; Melton, Jerry; Lawless, Brenda; Combs, Linda

    Data from the Texas Assessment of Academic Skills (TAAS) reveal that gains in performance for the African American student population of Region VII of the state's educational system were not keeping pace with the performance of African Americans in the rest of Texas. This study investigated practices in school districts in the region in which…

  7. New data on African health professionals abroad

    Directory of Open Access Journals (Sweden)

    Clemens Michael A

    2008-01-01

    Full Text Available Abstract Background The migration of doctors and nurses from Africa to developed countries has raised fears of an African medical brain drain. But empirical research on the causes and effects of the phenomenon has been hampered by a lack of systematic data on the extent of African health workers' international movements. Methods We use destination-country census data to estimate the number of African-born doctors and professional nurses working abroad in a developed country circa 2000, and compare this to the stocks of these workers in each country of origin. Results Approximately 65,000 African-born physicians and 70,000 African-born professional nurses were working overseas in a developed country in the year 2000. This represents about one fifth of African-born physicians in the world, and about one tenth of African-born professional nurses. The fraction of health professionals abroad varies enormously across African countries, from 1% to over 70% according to the occupation and country. Conclusion These numbers are the first standardized, systematic, occupation-specific measure of skilled professionals working in developed countries and born in a large number of developing countries.

  8. British African Caribbean Women and Depression

    Science.gov (United States)

    Adkison-Bradley, Carla; Maynard, Donna; Johnson, Phillip; Carter, Stephaney

    2009-01-01

    Depression is a common condition among women in the United Kingdom. However, little is known about the context of depression among British African Caribbean women. This article offers a preliminary discussion regarding issues and information pertaining to depression among British African Caribbean women. Characteristics and symptoms of depression…

  9. An African VLBI network of radio telescopes

    CERN Document Server

    Gaylard, M J; Combrinck, L; Booth, R S; Buchner, S J; Fanaroff, B L; MacLeod, G C; Nicolson, G D; Quick, J F H; Stronkhorst, P; Venkatasubramani, T L

    2014-01-01

    The advent of international wideband communication by optical fibre has produced a revolution in communications and the use of the internet. Many African countries are now connected to undersea fibre linking them to other African countries and to other continents. Previously international communication was by microwave links through geostationary satellites. These are becoming redundant in some countries as optical fibre takes over, as this provides 1000 times the bandwidth of the satellite links. In the 1970's and 1980's some two dozen large (30 m diameter class) antennas were built in various African countries to provide the satellite links. Twenty six are currently known in 19 countries. As these antennas become redundant, the possibility exists to convert them for radio astronomy at a cost of roughly one tenth that of a new antenna of similar size. HartRAO, SKA Africa and the South African Department of Science and Technology (DST) have started exploring this possibility with some of the African countries...

  10. The past, present and future of African dust

    Science.gov (United States)

    Evan, Amato T.; Flamant, Cyrille; Gaetani, Marco; Guichard, Françoise

    2016-03-01

    African dust emission and transport exhibits variability on diurnal to decadal timescales and is known to influence processes such as Amazon productivity, Atlantic climate modes, regional atmospheric composition and radiative balance and precipitation in the Sahel. To elucidate the role of African dust in the climate system, it is necessary to understand the factors governing its emission and transport. However, African dust is correlated with seemingly disparate atmospheric phenomena, including the El Niño/Southern Oscillation, the North Atlantic Oscillation, the meridional position of the intertropical convergence zone, Sahelian rainfall and surface temperatures over the Sahara Desert, all of which obfuscate the connection between dust and climate. Here we show that the surface wind field responsible for most of the variability in North African dust emission reflects the topography of the Sahara, owing to orographic acceleration of the surface flow. As such, the correlations between dust and various climate phenomena probably arise from the projection of the winds associated with these phenomena onto an orographically controlled pattern of wind variability. A 161-year time series of dust from 1851 to 2011, created by projecting this wind field pattern onto surface winds from a historical reanalysis, suggests that the highest concentrations of dust occurred from the 1910s to the 1940s and the 1970s to the 1980s, and that there have been three periods of persistent anomalously low dust concentrations—in the 1860s, 1950s and 2000s. Projections of the wind pattern onto climate models give a statistically significant downward trend in African dust emission and transport as greenhouse gas concentrations increase over the twenty-first century, potentially associated with a slow-down of the tropical circulation. Such a dust feedback, which is not represented in climate models, may be of benefit to human and ecosystem health in West Africa via improved air quality and

  11. South African AIDS plan criticised.

    Science.gov (United States)

    Sidley, P

    1998-10-17

    In a television broadcast, Deputy President Mbeki of South Africa announced a campaign against HIV/AIDS that would involve coordination between various government departments and nongovernmental organizations. Mbeki, who is associated with Virodene (a drug treatment for AIDS that is considered a scam), replaced President Mandela at the last minute in the broadcast. Two days after the broadcast, the government refused to support treatment of pregnant women infected with HIV with zidovudine to prevent transmission of the virus to the baby. The treatment is considered cost-effective by AIDS workers and public health officials. According to Mark Heywood of the AIDS law project at Witwatersrand University, 16% of pregnant women attending antenatal clinics were HIV-positive in 1997; this means that about 3 million South Africans (8% of the population) were living with HIV. Heywood said that the government believes there are 1500 new cases daily. By the end of 1998, 3.5 million South Africans will be living with HIV. Although the government is asking other sectors to join in the campaign, what the government is doing is unclear. Mother-to-child transmission of HIV is second only to transmission of the virus through heterosexual sex in South Africa. PMID:9841037

  12. Occurrence of Sciadicleithrum mexicanum Kritsky, Vidal-Martinez et Rodríguez-Canul, 1994 (Monogenea: Dactylogyridae in the Cichlid Cichlasoma urophthalmus from a flooded quarry in Yucatan, Mexico

    Directory of Open Access Journals (Sweden)

    E. F. Mendoza-Franco

    1995-06-01

    Full Text Available Cichlids, Cichlasoma urophthalmus, collected in a flooded quarry in the Yucatan Peninsula, Mexico, from January through June 1992, had high levels of infection with the ancyrocephaline Sciadicleithrum mexicanum (Monogena: Dactylogyridade in all montlhly samples. Neither occurrence nor maturation of the worms eshibited any pronounced monthly fluctuation. The infection rate was found to be sizedependent, greater in longer fish. The worms occurred on primary lamellae of gill filaments of all arches, with lower numbers of parasites attached to the fourth gill arch. Otherwise, there was no significant site preference of worms. Only minor histopathological changes were found at the sites of attachment, and these were restricted to the epithelial cells of the primary lamellae of thegill filaments. The lack of seasonal periodicity in this tropical monogenean is compared to seasonal cycles typical of temperate species.

  13. Incipient sympatric speciation in Midas cichlid fish from the youngest and one of the smallest crater lakes in Nicaragua due to differential use of the benthic and limnetic habitats?

    Science.gov (United States)

    Kautt, Andreas F; Machado-Schiaffino, Gonzalo; Torres-Dowdall, Julian; Meyer, Axel

    2016-08-01

    Understanding how speciation can occur without geographic isolation remains a central objective in evolutionary biology. Generally, some form of disruptive selection and assortative mating are necessary for sympatric speciation to occur. Disruptive selection can arise from intraspecific competition for resources. If this competition leads to the differential use of habitats and variation in relevant traits is genetically determined, then assortative mating can be an automatic consequence (i.e., habitat isolation). In this study, we caught Midas cichlid fish from the limnetic (middle of the lake) and benthic (shore) habitats of Crater Lake Asososca Managua to test whether some of the necessary conditions for sympatric speciation due to intraspecific competition and habitat isolation are given. Lake As. Managua is very small (<900 m in diameter), extremely young (maximally 1245 years of age), and completely isolated. It is inhabited by, probably, only a single endemic species of Midas cichlids, Amphilophus tolteca. We found that fish from the limnetic habitat were more elongated than fish collected from the benthic habitat, as would be predicted from ecomorphological considerations. Stable isotope analyses confirmed that the former also exhibit a more limnetic lifestyle than the latter. Furthermore, split-brood design experiments in the laboratory suggest that phenotypic plasticity is unlikely to explain much of the observed differences in body elongation that we observed in the field. Yet, neutral markers (microsatellites) did not reveal any genetic clustering in the population. Interestingly, demographic inferences based on RAD-seq data suggest that the apparent lack of genetic differentiation at neutral markers could simply be due to a lack of time, as intraspecific competition may only have begun a few hundred generations ago. PMID:27551387

  14. South African Association of Physicists in Medicine and Biology: 27. Annual congress, 11-13 Mar 1987, BLoemfontein

    International Nuclear Information System (INIS)

    The twenty-seventh annual congress of the South African Association of Physicists in Medicine and Biology was held from 11-13 March 1987, in Bloemfontein. Papers delivered at the conference covered subjects like medical physics, radiotherapy, computed tomography, scintigraphy, radiation doses and dosimetry and radioisotopes in diagnosis

  15. Educational Adaptation and Pan-Africanism: Trends in Africa.

    Science.gov (United States)

    Marah, John Karefah

    1987-01-01

    European colonialists believed that Africans should be educated in African traditional values, and that Africans should be made into dedicated workers, not holders of power. The African nationalists of the 1960s, in contrast, rejected most of the arduous aspects of European education as instruments of domination, and lay the foundation for the…

  16. 76 FR 6519 - National African American History Month, 2011

    Science.gov (United States)

    2011-02-04

    ... imagined, African Americans have strengthened our Nation by leading reforms, overcoming obstacles, and... of African Americans to our Nation's history and identity. This year's theme, ``African Americans and... enslaved within rebellious areas, he also opened the door for African Americans to join the Union...

  17. Magadi tilapia ecological specialization: filling the early gap in the speciation continuum.

    Science.gov (United States)

    Pinho, Catarina; Faria, Rui

    2016-04-01

    Cichlid fish are well known for their high speciation rates, which are usually accompanied by spectacular and rapid diversification in eco-morphological and secondary sexual traits. This is best illustrated by the famous repeated explosive radiations in the African Great Lakes Tanganyika, Malawi and Victoria, each lake harbouring several hundreds of mostly endemic species. Correspondingly, cichlids diversified very rapidly in many other lakes across their range. Although the larger radiations, unparalleled in vertebrates, are certainly the most intriguing, they are also the most intricate and difficult to address because of their complex nature. This is where smaller, simpler systems may prove to be the most useful. In this issue of Molecular Ecology, Kavembe et al. (2016) report very recent genetic diversification accompanied by ecological specialization in cichlids of the small and ecologically extreme Lake Magadi, in Kenya. Combining geometric morphometrics, stable isotope analysis, population genomics using RADSeq data and coalescent-based modelling techniques, the authors characterize the eco-morphological differences between genetically distinct populations of Magadi tilapia (Alcolapia grahami), which are consistent with the different environmental conditions they experience, and infer their history of divergence. The simplicity of the focal system and the use of a multidisciplinary approach make this work particularly important for our understanding of the early stages of speciation, in both cichlids and other organisms. PMID:27012820

  18. African widows: anthropological and historical perspectives.

    Science.gov (United States)

    Cattell, Maria G

    2003-01-01

    Variety characterizes widows' experiences around the world and in Africa south of the Sahara. This article explores the socioeconomic and cultural contexts of African widowhood, using anthropological studies in a number of African societies, including the author's research among Abaluyia of western Kenya. Some features of African widowhood are characteristic of African women's lives regardless of their marital status: their embeddedness in kinship systems and dependence on those systems for claims to productive resources, their economic self-reliance (which does not mean prosperity), strongly gendered divisions of labor, and the pervasiveness of patriarchal gender relations. Other features are specific to widowhood, including remarriage, issues of personal autonomy, and loss of status, access to productive resources and social support. Colonial and postcolonial historical transformations, including Africa's current dire economic situation and the AIDS epidemic, are considered in relation to widows' lives. An interesting question (given the theme of this edited volume) is whether a husband' s death puts African widows "on their own again," and whether, given African systems of kinship and marriage, most African women (and indeed men, too) can ever be said to be "on their own." PMID:14604001

  19. Radiation Inactivation of Viruses in Infected Products

    International Nuclear Information System (INIS)

    Full text: The effects of gamma radiation on foot-and-mouth disease virus in vitro and in situ have been studied. The data so far obtained show that a dose of 2 Mrad is required to inactivate virus in infected animal carcasses. But the dose may adversely affect the organoleptic quality of the meat. Experiments in vitro and in situ are necessary to study the effects of ionizing radiation on other viruses, such as rinderpest, swine fever and African swine fever-viruses, associated with animal products. Radiation may offer a possible means of eliminating the virus titre in many animal products and solve consequent quarantine problems. (author)

  20. The Economics of the African Media

    OpenAIRE

    Cage, Julia

    2014-01-01

    The focus of this chapter is on the economics of sub-Saharan African media. Using the history of sub-Saharan African newspapers as well as historical evidence from Europe and the United States, I study the emergence of market-oriented journalism and of an independent and informative press in sub-Saharan Africa. I document the extent to which sub-Saharan African newspapers have followed the same development steps than newspapers in other countries, moving from living off patronage and governme...

  1. MISCONCEPTIONS OF DEPRESSION IN AFRICAN AMERICANS

    Directory of Open Access Journals (Sweden)

    Zohaib eSohail

    2014-06-01

    Full Text Available Major depression is a very common disabling disorder. Although the relationship between race and depression is complex, depression affects all races, all ethnic and geographic locations as well as all age groups. The prevalence of depression in African Americans is controversial, due to the paucity of research. The deficit in the knowledge and skills in treating depression in African Americans have not been adequately addressed so far. Inadequate and insufficient data on African Americans contributes to the problems of under diagnoses, misdiagnosis and under treatment of depression. This article will highlight the existing problem of depression in Afro American with a focus on diagnostic and treatment issues.

  2. The African concept of caring for life

    Directory of Open Access Journals (Sweden)

    Maake Masango

    2005-10-01

    Full Text Available This article analyses the village concept of caring among African people. The old pattern of caring was based on the concept of ubuntu (humanity which respects people, because they are created in the imago Dei. Then the article compares the western concept of caring, which is based on individualism and people's privacy. Finally, economy, globalisation and this western concept are analysed. The impact of the above concepts affects Africans in urban areas, who are caught up in the two worlds, namely the African and western worlds.

  3. Mandela’s Favourite African Folktales

    OpenAIRE

    Carmen Concilio

    2014-01-01

    In this essay I would like to examine the selection of African tales that Nelson Mandela took care to leave as heritage to the future generations, not only to children, and not only to African children. The fact that a political leader, ex freedom fighter and political prisoner dedicated his time to the collection and editing of stories from all over the African continent to be addressed to new readers as simple entertainment or as educational tools clearly testifies to the great humanity, cu...

  4. AFRA. African Regional Co-operative Agreement

    International Nuclear Information System (INIS)

    This publication provides an outline of the African Regional Co-operation Agreement for research, development and training related to nuclear science and technology (AFRA). The agreement stems from an initiative of several African member states of the IAEA to get the agency to help establish an African regional arrangement which would be similar to arrangements which were already in place in the Asian and Latin American regions. Through this regional approach to development, AFRA seeks to accelerate moves toward self-sufficiency in scientific disciplines and appropriate technologies by coordinating intellectual and physical resources and disseminating innovative methods and practices in a cost-effective manner

  5. 21st Century South African Science Fiction

    Directory of Open Access Journals (Sweden)

    CARAIVAN LUIZA

    2014-12-01

    Full Text Available The paper analyses some aspects of South African science fiction, starting with its beginnings in the 1920s and focusing on some 21st century writings. Thus Lauren Beukes’ novels Moxyland (2008 and Zoo City (2010 are taken into consideration in order to present new trends in South African literature and the way science fiction has been marked by Apartheid. The second South African science fiction writer whose writings are examined is Henrietta Rose-Innes (with her novel Nineveh, published in 2011 as this consolidates women's presence in the SF world.

  6. The African American Wellness Village in Portland, Ore

    OpenAIRE

    McKeever, Corliss; Koroloff, Nancy; Faddis, Collaine

    2006-01-01

    More than 80% of African Americans in Oregon reside in the Portland metropolitan area; African Americans comprise 1.7% of the state's population. Although relatively small, the African American population in the state experiences substantial health disparities. The African American Health Coalition, Inc was developed to implement initiatives that would reduce these disparities and to promote increased communication and trust between the African American community and local institutions and or...

  7. Symptomatology of peripheral neuropathy in an African language.

    Directory of Open Access Journals (Sweden)

    Asma Shaikh

    Full Text Available The terminology used to describe neuropathic pain appears to be conserved across languages, which facilitates the translation of validated neuropathic pain screening tools into other languages. However, this assumption has not been assessed in an African language. Therefore we investigated the terminology used by 54 patients whose native language was isiZulu, a major Bantu language of Africa, when describing their symptomatic HIV-associated sensory neuropathy. Also, because English is a commonly spoken second-language in the region, we assessed these patients' knowledge and understanding of 21 English terms commonly used to describe neuropathic pain. English translations of the most commonly used isiZulu symptom descriptors included: "hot/burning" (50%, "cramping" (35%, "painful/sore/aching" (32%, "itching" (22%, "numb" (22%, "cold/freezing" (17%, and "stabbing/pricking/pins-and-needles" (13%. Thus, the isiZulu terminology to describe neuropathic pain was very similar to that used in non-African languages. However, knowledge and understanding of English neuropathic pain descriptors by these non-native English speakers was highly variable. For example, knowledge of English terms ranged from >98% ("hot", "cold/freezing", "cramping" to 90% ("hot", "burning", "cramping" to <35% ("tingling", "jumping", "shooting", "radiating". In conclusion, we show significant similarity in the terms used to describe neuropathic pain in isiZulu compared to non-African languages, thus indicating that translation of existing neuropathic pain screening tools into this, and possibly other Bantu languages, is a viable option. However, the usefulness of English-language screening tools in this non-native English speaking population may be limited.

  8. Palaearctic-African Bird Migration

    DEFF Research Database (Denmark)

    Iwajomo, Soladoye Babatola

    -Saharan migrants than autumn migration. Information about the behavior and interactions of migrants during the nonbreeding season in sub-Saharan Africa is also scarce for many species. Furthermore, very little is known about intra-African migration. This thesis summarizes my research on the autumn migration of...... still unknown. The fourth paper and one manuscript investigate the behavior of garden warblers Sylvia borin, during the non-breeding season in Nigeria. The first paper shows that the species also utilizes habitats south of the savannah region, presumably on its way to the final goal area. Individuals...... also molt their flight feathers at this location and intraspecific interactions are non-aggressive. The second manuscript investigates whether variations in the timing of migration of wader species at a stopover site in southeast Sweden is influence by local or regional climatic variables. The...

  9. African diatom palaeoecology and biostratigraphy

    Science.gov (United States)

    Gasse, F.; Fourtanier, E.

    This paper illustrates the different types of information which can be deduced from African diatoms studies. The first section is devoted to the reconstruction of palaeoenvironments. The accuracy of ecological data (estimates of ecological variables e.g. types of habitats, water chemistry…) depends on the times scale and on the spatial scale considered: short-term environments in a given waterbody, environmental evolution during individual humid episodes considered locally or regionally, long-term changes in diatom flora induced by major climatic tendencies at a regional or continental scale. One then summarizes our present state of knowledge in diatom biostratigraphy in Africa. Several centric taxa, belonging to the genera Aulacoseira, Mesodictyon, Cyclotella, Stephanodiscus and Cyclostephanos appear to have limited stratigraphical ranges and to be good chronological markers.

  10. Africa Pentecostalized? Understanding the African appropriation of Pentecostalism in light of African perspectives

    OpenAIRE

    Østhassel, Ole Aleksander

    2013-01-01

    I want to prepare an understanding of why Pentecostalism seems to be so attractive in Africa. I will outline Ogbu Kalu's understanding of a resonance between African traditional culture and Pentecostalism, and then add perspectives from other African scholars. And the research problem follows: How can we understand the appropriation of Pentecostalism in Africa in light of Ogbu Kalu? Research questions will be: In what way do Pentecostalism and African traditional cult...

  11. Enhancing the African bioethics initiative

    Directory of Open Access Journals (Sweden)

    Ogundiran Temidayo O

    2004-10-01

    Full Text Available Abstract Background Medical ethics has existed since the time of Hippocrates. However, formal training in bioethics did not become established until a few decades ago. Bioethics has gained a strong foothold in health sciences in the developed world, especially in Europe and North America. The situation is quite different in many developing countries. In most African countries, bioethics – as established and practiced today in the west- is either non-existent or is rudimentary. Discussion Though bioethics has come of age in the developed and some developing countries, it is still largely "foreign" to most African countries. In some parts of Africa, some bioethics conferences have been held in the past decade to create research ethics awareness and ensure conformity to international guidelines for research with human participants. This idea has arisen in recognition of the genuine need to develop capacity for reviewing the ethics of research in Africa. It is also a condition required by external sponsors of collaborative research in Africa. The awareness and interest that these conferences have aroused need to be further strengthened and extended beyond research ethics to clinical practice. By and large, bioethics education in schools that train doctors and other health care providers is the hook that anchors both research ethics and clinical ethics. Summary This communication reviews the current situation of bioethics in Africa as it applies to research ethics workshops and proposes that in spite of the present efforts to integrate ethics into biomedical research in Africa, much still needs to be done to accomplish this. A more comprehensive approach to bioethics with an all-inclusive benefit is to incorporate formal ethics education into health training institutions in Africa.

  12. Radiation protection

    International Nuclear Information System (INIS)

    This work define procedures and controls about ionizing radiations. Between some definitions it found the following topics: radiation dose, risk, biological effects, international radioprotection bodies, workers exposure, accidental exposure, emergencies and radiation protection

  13. Isotropic Radiators

    CERN Document Server

    Matzner, H; Matzner, Haim; Donald, Kirk T. Mc

    2003-01-01

    We give two examples of antennas with isotropic radiation patterns. Because these involve elliptically polarized radiation, they evade the "hairy-ball theorem" that suggests isotropic radiation would be impossible.

  14. Radiation dosimetry

    CERN Document Server

    Hine, Gerald J; Hine, Gerald J

    1956-01-01

    Radiation Dosimetry focuses on the advancements, processes, technologies, techniques, and principles involved in radiation dosimetry, including counters and calibration and standardization techniques. The selection first offers information on radiation units and the theory of ionization dosimetry and interaction of radiation with matter. Topics include quantities derivable from roentgens, determination of dose in roentgens, ionization dosimetry of high-energy photons and corpuscular radiations, and heavy charged particles. The text then examines the biological and medical effects of radiation,

  15. Extraordinary life history in African annual fishes

    Czech Academy of Sciences Publication Activity Database

    Blažek, Radim; Polačik, Matej; Reichard, Martin

    Bujumbura: University of Burundi, 2013. s. 52-53. [International Conference of the Pan African Fish and Fisheries Association (PAFFA) /5./. 16.09.2013-20.09.2013, Bujumbura] Institutional support: RVO:68081766 Keywords : Nothobranchius * Mozambique Subject RIV: EG - Zoology

  16. African Studies Abstracts Online: number 28, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 28 (2009). African Studies Centre, Leiden.

  17. African Studies Abstracts Online: number 25, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 25 (2009). African Studies Centre, Leiden.

  18. African Studies Abstracts Online: number 10, 2005

    OpenAIRE

    African Studies Centre

    2005-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 10 (2005). African Studies Centre, Leiden.

  19. African Studies Abstracts Online: number 36, 2011

    OpenAIRE

    African Studies Centre

    2011-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 36 (2011). African Studies Centre, Leiden.

  20. African Studies Abstracts Online: number 23, 2008

    OpenAIRE

    African Studies Centre

    2008-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 23 (2008). African Studies Centre, Leiden.

  1. African Studies Abstracts Online: number 30, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 30 (2010). African Studies Centre, Leiden.

  2. African Studies Abstracts Online: number 20, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 20 (2007). African Studies Centre, Leiden.

  3. African Studies Abstracts Online: number 50, 2015

    OpenAIRE

    African Studies Centre

    2015-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 50 (2015). African Studies Centre, Leiden.

  4. African Studies Abstracts Online: number 34, 2011

    OpenAIRE

    African Studies Centre

    2011-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 34 (2011). African Studies Centre, Leiden.

  5. African Studies Abstracts Online: number 11, 2005

    OpenAIRE

    African Studies Centre

    2005-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 11 (2005). African Studies Centre, Leiden.

  6. African Studies Abstracts Online: number 52, 2015

    OpenAIRE

    African Studies Centre

    2015-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 52 (2015). African Studies Centre, Leiden.

  7. African Studies Abstracts Online: number 15, 2006

    OpenAIRE

    African Studies Centre

    2006-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 15 (2006). African Studies Centre, Leiden.

  8. African Studies Abstracts Online: number 48, 2014

    OpenAIRE

    African Studies Centre

    2014-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 48 (2014). African Studies Centre, Leiden.

  9. African Studies Abstracts Online: number 22, 2008

    OpenAIRE

    African Studies Centre

    2008-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 22 (2008). African Studies Centre, Leiden.

  10. African Studies Abstracts Online: number 43, 2013

    OpenAIRE

    African Studies Centre

    2013-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 43 (2013). African Studies Centre, Leiden.

  11. African Studies Abstracts Online: number 17, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 17 (2007). African Studies Centre, Leiden.

  12. African Studies Abstracts Online: number 18, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 18 (2007). African Studies Centre, Leiden.

  13. African Studies Abstracts Online: number 38, 2012

    OpenAIRE

    African Studies Centre

    2012-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 38 (2012). African Studies Centre, Leiden.

  14. African Studies Abstracts Online: number 9, 2005

    OpenAIRE

    African Studies Centre

    2005-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 9 (2005). African Studies Centre, Leiden.

  15. African Studies Abstracts Online: number 31, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 31 (2010). African Studies Centre, Leiden.

  16. African Studies Abstracts Online: number 40, 2012

    OpenAIRE

    African Studies Centre

    2012-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 40 (2012). African Studies Centre, Leiden.

  17. African Studies Abstracts Online: number 27, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 27 (2009). African Studies Centre, Leiden.

  18. African Studies Abstracts Online: number 37, 2012

    OpenAIRE

    African Studies Centre

    2012-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 37 (2012). African Studies Centre, Leiden.

  19. African Studies Abstracts Online: number 26, 2009

    OpenAIRE

    African Studies Centre

    2009-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 26 (2009). African Studies Centre, Leiden.

  20. African Studies Abstracts Online: number 29, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 29 (2010). African Studies Centre, Leiden.

  1. African Studies Abstracts Online: number 33, 2011

    OpenAIRE

    African Studies Centre

    2011-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 33 (2011). African Studies Centre, Leiden.

  2. African Studies Abstracts Online: number 42, 2013

    OpenAIRE

    African Studies Centre

    2013-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 42 (2013). African Studies Centre, Leiden.

  3. African Studies Abstracts Online: number 45, 2014

    OpenAIRE

    African Studies Centre

    2014-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 45 (2014). African Studies Centre, Leiden.

  4. African Studies Abstracts Online: number 19, 2007

    OpenAIRE

    African Studies Centre

    2007-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 19 (2007). African Studies Centre, Leiden.

  5. African Studies Abstracts Online: number 46, 2014

    OpenAIRE

    African Studies Centre

    2014-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 46 (2014). African Studies Centre, Leiden.

  6. African Studies Abstracts Online: number 32, 2010

    OpenAIRE

    African Studies Centre

    2010-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 32 (2010). African Studies Centre, Leiden.

  7. African Studies Abstracts Online: number 51, 2015

    OpenAIRE

    African Studies Centre

    2015-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 51 (2015). African Studies Centre, Leiden.

  8. African Studies Abstracts Online: number 16, 2006

    OpenAIRE

    African Studies Centre

    2006-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 16 (2006). African Studies Centre, Leiden.

  9. African Studies Abstracts Online: number 24, 2008

    OpenAIRE

    African Studies Centre

    2008-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 24 (2008). African Studies Centre, Leiden.

  10. African Studies Abstracts Online: number 39, 2012

    OpenAIRE

    African Studies Centre

    2012-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 39 (2012). African Studies Centre, Leiden.

  11. African Studies Abstracts Online: number 54, 2016

    OpenAIRE

    African Studies Centre Leiden

    2016-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 54 (2016). African Studies Centre, Leiden.

  12. African Studies Abstracts Online: number 47, 2014

    OpenAIRE

    African Studies Centre

    2014-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 47 (2014). African Studies Centre, Leiden.

  13. African Studies Abstracts Online: number 21, 2008

    OpenAIRE

    African Studies Centre

    2008-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 21 (2008). African Studies Centre, Leiden.

  14. African Studies Abstracts Online: number 35, 2011

    OpenAIRE

    African Studies Centre

    2011-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 35 (2011). African Studies Centre, Leiden.

  15. African Studies Abstracts Online: number 44, 2013

    OpenAIRE

    African Studies Centre

    2013-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 44 (2013). African Studies Centre, Leiden.

  16. African Studies Abstracts Online: number 53, 2016

    OpenAIRE

    African Studies Centre

    2016-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 53 (2016). African Studies Centre, Leiden.

  17. African Studies Abstracts Online: number 49, 2015

    OpenAIRE

    African Studies Centre

    2015-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 49 (2015). African Studies Centre, Leiden.

  18. African Studies Abstracts Online: number 41, 2013

    OpenAIRE

    African Studies Centre

    2013-01-01

    ASA Online provides a quarterly overview of journal articles and edited works on Africa in the field of the social sciences and the humanities available in the ASC library. Issue 41 (2013). African Studies Centre, Leiden.

  19. Cardiac assessment of African hedgehogs (Atelerix albiventris).

    Science.gov (United States)

    Black, Peter A; Marshall, Cecilia; Seyfried, Alice W; Bartin, Anne M

    2011-03-01

    Cardiomyopathy is a common finding in captive African hedgehogs (Atelerix albiventris) at postmortem exam. To date, treatment attempts have been mostly empirical and unrewarding. The objective of this study was to determine reference cardiac values for captive African hedgehogs based on echocardiogram, electrocardiogram (ECG), and radiographs. Adult African hedgehogs with no clinical signs of cardiac disease (n = 13) were selected. Each animal was anesthetized with isoflurane via facemask and an echocardiogram, ECG, and radiographs were performed. Standard measurements were taken and the descriptive statistics performed. Values were comparable to limited data available in other hedgehog species and other similar-sized exotic species. Two animals were removed from consideration of reference values due to valvular defects that were considered significant. These data are the first establishing cardiac parameters in normal African hedgehogs using radiographic cardiac measurement, echocardiogram, and ECG. Evaluating animals with possible cardiomyopathy may allow for earlier diagnosis and more successful treatment. PMID:22946370

  20. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... the African-American that we treat this as what it is -- an epidemic. Winston Dyer: My introduction ... being ignorant to prostate cancer -- and not knowing what it was -- that was my first, first, first- ...

  1. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... runs higher. We really don't know. But I would strongly suggest to the African-American that ... then my dad four months later. And then I was told by doctors that I should be ...

  2. Development of 'Serunding' from African catfish

    DEFF Research Database (Denmark)

    Juhari, Nurul Hanisah Binti; MK, Zainol; MM, Masduki

    This research was conducted to develop serunding from African catfish (Clarias gariepinus). Proximate analysis, physical analysis, ascorbic acid analysis, mineral analysis and sensory evaluation were carried out to determine the nutrient compositions and consumer acceptance towards the products. ...

  3. The innovative African kilowatt-hour

    International Nuclear Information System (INIS)

    There is a worldwide resurgence of interest in pricing electricity. Whether motivated by deregulation and the treat of competition (as in England and New Zealand) or by restructuring of regulatory goals to encourage competition or conservation (as in the United States), electricity suppliers and distributors are seeing pricing as a means of safeguarding, maintaining, increasing sales. South Africa is no exception in this regard. Past and proposed new developments in electricity pricing in the South African electricity supply industry are discussed, in response to pressures across several fronts: pressures from customers to reduce electricity prices to facilitate growth and survival in the South African economy; the national electrification program; the appointment of the National Electricity Regulator; moves by Southern African electricity utilities to establish a Southern African grid. The current status of electricity pricing, metering, demand profile research and demand management in South Africa are overviewed. (author)

  4. The innovative African kilowatt-hour

    Energy Technology Data Exchange (ETDEWEB)

    Calitz, A.C. [ESKOM, Johannesburg (South Africa)

    1996-12-31

    There is a worldwide resurgence of interest in pricing electricity. Whether motivated by deregulation and the treat of competition (as in England and New Zealand) or by restructuring of regulatory goals to encourage competition or conservation (as in the United States), electricity suppliers and distributors are seeing pricing as a means of safeguarding, maintaining, increasing sales. South Africa is no exception in this regard. Past and proposed new developments in electricity pricing in the South African electricity supply industry are discussed, in response to pressures across several fronts: pressures from customers to reduce electricity prices to facilitate growth and survival in the South African economy; the national electrification program; the appointment of the National Electricity Regulator; moves by Southern African electricity utilities to establish a Southern African grid. The current status of electricity pricing, metering, demand profile research and demand management in South Africa are overviewed. (author).

  5. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... Walker: The researchers don't know exactly why. It is suggested that maybe our diet, maybe our ... African-American that we treat this as what it is -- an epidemic. Winston Dyer: My introduction to ...

  6. Development of West African Rainy Seasons (Invited)

    Science.gov (United States)

    Cook, K. H.

    2013-12-01

    The development of West African rainy seasons in the observed climatology can be understood in terms of two factors: continentality, i.e., the shape and placement of the African continent, and solar forcing. First, the observed features of the West African spring and summer precipitation climatology that distinguish it from the precipitation climatology of the tropical Atlantic to the east and Central/Eastern Africa to the west are presented. These include a lingering of the precipitation maximum along the Guinean coast in June and the apparent sudden movement of the precipitation maximum into the Sahel in early July. Then, these distinguishing features of the West Africa precipitation climatology are explained in terms of the regional dynamics and, finally, related to continentality and solar forcing through the roles of the African easterly jet, land surface temperature, and seasonally-varying SSTs.

  7. Development of 'Serunding' from African catfish

    OpenAIRE

    Juhari, Nurul Hanisah Binti; MK, Zainol; MM, Masduki

    2009-01-01

    This research was conducted to develop serunding from African catfish (Clarias gariepinus). Proximate analysis, physical analysis, ascorbic acid analysis, mineral analysis and sensory evaluation were carried out to determine the nutrient compositions and consumer acceptance towards the products. samples of serunding were prepared with 3 different sizes (30-40cm, 40-50cm, 50-60cm) of African catfish and control was prepared using round scad fish ('ikan selayang') with same amount of fish flesh...

  8. Glimmering Utopias: 50 Years of African Film

    OpenAIRE

    Cassis Kilian

    2011-01-01

    The history of African film began in the 1960s with the independence of the colonies. Despite all kinds of political and economic difficulties, numerous films have been made since then, featuring wide-ranging processes of consolidation, differentiation and transformation which were characteristic of post-colonial sub-Saharan Africa. However, these feature films should not merely be viewed as back references to specifically African problems. The glimmering fictions are imagination spaces. They...

  9. Informed consent comprehension in African research settings

    OpenAIRE

    Afolabi, M.; Okebe, J.; McGrath, N.; Larson, H; Bojang, K.; Chandramohan, D.

    2014-01-01

    Objective Previous reviews on participants' comprehension of informed consent information have focused on developed countries. Experience has shown that ethical standards developed on Western values may not be appropriate for African settings where research concepts are unfamiliar. We undertook this review to describe how informed consent comprehension is defined and measured in African research settings. Methods We conducted a comprehensive search involving five electronic databa...

  10. Corynebacterial pneumonia in an African hedgehog.

    Science.gov (United States)

    Raymond, J T; Williams, C; Wu, C C

    1998-04-01

    A 3-mo-old, male African hedgehog (Atelerix albiventris) was anorectic and lethargic for a period of 3 days prior to death. Necropys revealed lungs that were diffusely firm, dark red, and dorsally adhered by fibrinous tags to the pericardial sac. Histopathology revealed necrosuppurative bronchopneumonia with pulmonary abscesses and suppurative pericarditis and myocarditis. A Corynebacterium sp. was isolated from the lungs. We believe this is the first reported case of corynebacterial pneumonia in an African hedgehog. PMID:9577794

  11. Intestinal lymphosarcoma in captive African hedgehogs.

    Science.gov (United States)

    Raymond, J T; Clarke, K A; Schafer, K A

    1998-10-01

    Two captive adult female African hedgehogs (Atelerix albiventris) had inappetance and bloody diarrhea for several days prior to death. Both hedgehogs had ulceration of the small intestine and hepatic lipidosis. Histopathology revealed small intestinal lymphosarcoma with metastasis to the liver. Extracellular particles that had characteristics of retroviruses were observed associated with the surface of some neoplastic lymphoid cells by transmission electron microscopy. These are the first reported cases of intestinal lymphosarcoma in African hedgehogs. PMID:9813852

  12. South African coal statistics 2006. Marketing manual

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-08-15

    The report shows that South African thermal exports increased 5% from 66.6Mt to 69.9Mt in 2005 and that the country was the world's third largest seaborne exporter of thermal coal last year. Covering local coal consumption, South African coal imports, exports, prices and qualities, the report offers a complete statistical review of 2005. The report also includes details on labour, individual collieries, export and rail infrastructure and Black Empowerment (BEE) companies.

  13. Contemporary Literature in the African Diaspora

    OpenAIRE

    Barrios Herrero, Olga; Bell, Bernard W.

    1997-01-01

    [ES] El libro es una colección de ensayos divididos entre las tres grandes secciones del libro: Literatura afroamericana, Literatura Afro-caribeña y Afro-latinoamericana y Literatura africana en inglés. [EN] The book is a collection of essays included in the three sections of the book: on African American Literature, Afro-Caribbean and Afro-Latin American Literature and African Literature in English.

  14. Coinfections in East African Shorthorn Zebu

    OpenAIRE

    Callaby, Rebecca

    2015-01-01

    The Infectious Diseases of East African Livestock (IDEAL) project followed 548 East African Shorthorn Zebu (EASZ) calves in Western Kenya for the first year of life and monitored the sequelae of infections by multiple parasites. More than 50 different parasites were identified during this time. The IDEAL project also gathered environmental information about the farm and collected phenotypic data on the calf and its dam. Calves were also genotyped for 55,777 single nucleotide po...

  15. The african protoproverbial in a multipolar world

    OpenAIRE

    Taiwo, Ọlọruntọba-Oju

    2014-01-01

    The proverb is a rhetorical universal and as such shares features across linguistic, ethnic and culture boundaries, thus making typological distinctions along ethnic or regional lines a daunting task. Further complicating this scenario within the African context is the relentless hybridization and subversion of the African proverb consequent on colonial contact and sundry postcolonial interventions. This twin trajectory, the conceptual universalism of the proverb and the relent...

  16. African American Culture and Hypertension Prevention

    OpenAIRE

    Peters, Rosalind M.; Aroian, Karen J.; Flack, John M.

    2006-01-01

    A qualitative study was done to explore attitudes and beliefs of African Americans regarding hypertension-preventive self-care behaviors. Five focus groups, with 34 participants, were held using interview questions loosely based on the Theory of Planned Behavior (TPB). Analysis revealed themes broadly consistent with the TPB, and also identified an overarching theme labeled “circle of culture.” The circle is a metaphor for ties that bind individuals within the larger African American communit...

  17. Language and Culture in African Postcolonial Literature

    OpenAIRE

    Asante-Darko, Kwaku

    2000-01-01

    In his article, "Language and Culture in African Postcolonial Literature," Kwaku Asante-Darko offers both conceptual basis and empirical evidence in support of the fact that critical issues concerning protest, authenticity, and hybridity in African post-colonial literature have often been heavily laden with nationalist and leftist ideological encumbrances, which tended to advocate the rejection of Western standards of aesthetics. One of the literary ramifications of nationalist/anti-colonial ...

  18. Demographics of South African Households - 1995

    OpenAIRE

    Rantho, Lillian

    2003-01-01

    This paper provides an overview of the demographics of the South African population based on the October Household Survey (OHS) and the Income and Expenditure Survey (IES), both conducted by Statistics South Africa in 1995. Figures and tables are used throughout to paint a picture of the structure of the South African population, both at household level (IES data) and individual level (OHS data). Specific reference is made to the racial and spatial composition of households and individuals, t...

  19. Economic Key to Sino-African Ties

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Following Chinese President Hu Jintao's visit to Africa's Morocco, Nigeria and Kenya in April, Chinese Premier Wen Jiabao is currently visiting seven African countries-Egypt, Ghana, Republic of Congo, Angola, South Africa, Tanzania and Uganda. Haile-Kiros Gessesse, Ethiopia's Ambassador to China, discussed with Beijing Review reporter Ni Yanshuo the future of the Sino-African relationship. As special envoy for the Forum on China-Africa Cooperation, he also expressed his expectations of the forum summit t...

  20. Weak interaction in the African Easterly Jet

    OpenAIRE

    A. Lenouo; F. Nkankam Kamga; Yepdjuo, E.

    2005-01-01

    Low-frequency, African Easterlies Waves (AEW) are examined as disturbances embedded in the mid-tropospheric easterly jet of the African low troposphere. The solution to the nonlinear vorticity equation relevant to the description of waves is sought in the form of triplet waves. The latest suggest a unified method to determine their kinetics characteristic and to explain the mechanism of energy exchange between their different modes. The period of energy interaction between different modes of ...

  1. Radiation Hydrodynamics

    Science.gov (United States)

    Mihalas, Dimitri

    Basic Radiation Theory Specific Intensity Photon Number Density Photon Distribution Function Mean Intensity Radiation Energy Density Radiation Energy Flux Radiation Momentum Density Radiation Stress Tensor (Radiation Pressure Tensor) Thermal Radiation Thermodynamics of Thermal Radiation and a Perfect Gas The Transfer Equation Absorption, Emission, and Scattering The Equation of Transfer Moments of the Transfer Equation Lorentz Transformation of the Transfer Equation Lorentz Transformation of the Photon 4-Momentum Lorentz Transformation of the Specific Intensity, Opacity, and - Emissivity Lorentz Transformation of the Radiation Stress Energy Tensor The Radiation 4-Force Density Vector Covariant Form of the Transfer Equation Inertial-Frame Equations of Radiation Hydrodynamics Inertial-Frame Radiation Equations Inertial-Frame Equations of Radiation Hydrodynamics Comoving-Frame Equation of Transfer Special Relativistic Derivation (D. Mihalas) Consistency Between Comoving-Frame and Inertial-Frame Equations Noninertial Frame Derivation (J. I. Castor) Analysis of O (v/c) Terms Lagrangian Equations of Radiation Hydrodynamics Momentum Equation Gas Energy Equation First Law of Thermodynamics for the Radiation Field First Law of Thermodynamics for the Radiating Fluid Mechanical Energy Equation Total Energy Equation Consistency of Different Forms of the Radiating-Fluid Energy - and Momentum Equations Consistency of Inertial-Frame and Comoving-Frame Radiation Energy - and Momentum Equations Radiation Diffusion Radiation Diffusion Nonequilibrium Diffusion The Problem of Flux Limiting Shock Propagation: Numerical Methods Acoustic Waves Numerical Stability Systems of Equations Implications of Shock Development Implications of Diffusive Energy Transport Illustrative Example Numerical Radiation Hydrodynamics Radiating Fluid Energy and Momentum Equations Computational Strategy Energy Conservation Formal Solution Multigroup Equations An Astrophysical Example Adaptive-Grid Radiation

  2. Dust-rainfall feedback in West African Sahel

    Science.gov (United States)

    Yu, Kailiang; D'Odorico, Paolo; Bhattachan, Abinash; Okin, Gregory S.; Evan, Amato T.

    2015-09-01

    Drought persistence in West African Sahel has often been explained as an effect of positive vegetation-atmosphere feedback associated with surface albedo or the partitioning of solar radiation into sensible and latent heat fluxes. An often overlooked aspect of land-atmosphere coupling results from vegetation controls on dust emissions and the ability of mineral aerosols to suppress precipitation. Here we first consider the case of local (endogenous) dynamics within the Sahel, whereby enhanced dust emissions resulting from a decrease in vegetation partly suppress precipitation, thereby further reducing vegetation cover. We then account for teleconnections between Sahel precipitation and exogenous (i.e., Saharan) dust emissions due to an increase in Saharan wind speed in years of above average Sahel precipitation. We find that in both cases vegetation-climate dynamics may have two stable states, one with low precipitation and high concentration of atmospheric dust and the other with high precipitation and lower levels of atmospheric dust.

  3. Influence of 21st century atmospheric and sea surface temperature forcing on West African climate

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Chris B [Stanford University; Ashfaq, Moetasim [ORNL; Diffenbaugh, Noah [Stanford University

    2011-01-01

    he persistence of extended drought events throughout West Africa during the 20th century has motivated a substantial effort to understand the mechanisms driving African climate variability, as well as the possible response to elevated greenhouse gas (GHG) forcing. We use an ensemble of global climate model experiments to examine the relative roles of future direct atmospheric radiative forcing and SST forcing in shaping potential future changes in boreal summer precipitation over West Africa. We find that projected increases in precipitation throughout the Western Sahel result primarily from direct atmospheric radiative forcing. The changes in atmospheric forcing generate a slight northward displacement and weakening of the African easterly jet (AEJ), a strengthening of westward monsoon flow onto West Africa and an intensification of the tropical easterly jet (TEJ). Alternatively, we find that the projected decreases in precipitation over much of the Guinea Coast region are caused by SST changes that are induced by the atmospheric radiative forcing. The changes in SSTs generate a weakening of the monsoon westerlies and the TEJ, as well as a decrease in low-level convergence and resultant rising air throughout the mid levels of the troposphere. Our experiments suggest a potential shift in the regional moisture balance of West Africa should global radiative forcing continue to increase, highlighting the importance of climate system feedbacks in shaping the response of regional-scale climate to global-scale changes in radiative forcing.

  4. Practical radiology education in South African Dental Schools, 1981

    International Nuclear Information System (INIS)

    The current position of practical preclinical and clinical training in dento-maxillo-facial radiography for dental students and oral hygiene students in South Africa is reviewed. Special attention is given to factors in methodology which have an influence on radiation protection. Results indicate that there is a fairly high degree of standardization in dento-maxillo-facial radiography instruction in South Africa. The preference for the lead-lined or shielded open-ended cones is in keeping with the tenets of radiation protection. The use of pointed cones for intraoral radiography is not a good choice, as this causes scatter radiation. The wide use of the Rinn XCP(R) filmholding device in South African dental schools for the parallelling technique lessens the chance of cone cutting, and hence reduces the likelihood of needing to reexpose the patient due to that technical error. Additionally, the parallelling technique allows a more accurate assessment of alveolar bone loss from periodontal disease, and allows a better judgement of the relationship between the roots of maxillary teeth and the floor of the maxillary sinus, than does the bisecting angle technique. During the past decade, fiarly consistent parameters have been developed in dento-maxillo-facial radiography concerning preclinical and clinical training of dental and oral hygiene students

  5. The East African rift system

    Science.gov (United States)

    Chorowicz, Jean

    2005-10-01

    This overview paper considers the East African rift system (EARS) as an intra-continental ridge system, comprising an axial rift. It describes the structural organization in three branches, the overall morphology, lithospheric cross-sections, the morphotectonics, the main tectonic features—with emphasis on the tension fractures—and volcanism in its relationships with the tectonics. The most characteristic features in the EARS are narrow elongate zones of thinned continental lithosphere related to asthenospheric intrusions in the upper mantle. This hidden part of the rift structure is expressed on the surface by thermal uplift of the rift shoulders. The graben valleys and basins are organized over a major failure in the lithospheric mantle, and in the crust comprise a major border fault, linked in depth to a low angle detachment fault, inducing asymmetric roll-over pattern, eventually accompanied by smaller normal faulting and tilted blocks. Considering the kinematics, divergent movements caused the continent to split along lines of preexisting lithospheric weaknesses marked by ancient tectonic patterns that focus the extensional strain. The hypothesis favored here is SE-ward relative divergent drifting of a not yet well individualized Somalian plate, a model in agreement with the existence of NW-striking transform and transfer zones. The East African rift system comprises a unique succession of graben basins linked and segmented by intracontinental transform, transfer and accommodation zones. In an attempt to make a point on the rift system evolution through time and space, it is clear that the role of plume impacts is determinant. The main phenomenon is formation of domes related to plume effect, weakening the lithosphere and, long after, failure inducing focused upper mantle thinning, asthenospheric intrusion and related thermal uplift of shoulders. The plume that had formed first at around 30 Ma was not in the Afar but likely in Lake Tana region (Ethiopia

  6. Radiative forcing associated with a springtime case of Bodélé and Sudan dust transport over West Africa

    OpenAIRE

    Lemaître, C; C. Flamant; Cuesta, J.; J.-C. Raut; Chazette, P.; P. Formenti; Pelon, J

    2010-01-01

    The radiative forcing due to mineral dust over West Africa is investigated using the radiative code STREAMER, as well as remote sensing and in situ observations gathered during the African Monsoon Multidisciplinary Analysis Special Observing Period (AMMA SOP). We focus on two days (13 and 14 June 2006) of an intense and long-lasting episode of dust being lifted in remote sources in Chad and Sudan and transported across West Africa in the African easterly jet region, during which airborne oper...

  7. Perceptions of African American and European American Teachers on the Education of African American Boys

    Science.gov (United States)

    Bacon, Ellen; Banks, Joy; Young, Kathryn; Jackson, Francesina R.

    2007-01-01

    The authors interviewed 27 teachers (16 African American and 11 European American) on instructional factors contributing to overidentification of behavior problems in African American boys. Interviews focused on teachers' perspectives of effective teachers, teacher-student relationships, and communication styles. Analysis of the interviews showed…

  8. Fat, fibre and cancer risk in African Americans and rural Africans

    NARCIS (Netherlands)

    O'Keefe, S.J.; Li, J.V.; Lahti, Leo; Ou, J.; Carbonero, F.; Khaled, M.; Postma, J.M.; Kinross, J.; Wahl, E.; Ruder, E.; Vipperla, K.; Naidoo, V.; Mtshali, L.; Tims, S.; Puylaert, P.G.B.; DeLany, J.; Krasinskas, A.; Benefiel, A.C.; Kaseb, H.O.; Newton, K.; Nicholson, J.K.; Vos, De W.M.; Gaskins, H.R.; Zoetendal, E.G.

    2015-01-01

    Rates of colon cancer are much higher in African Americans (65:100,000) than in rural South Africans (<5:100,000). The higher rates are associated with higher animal protein and fat, and lower fibre consumption, higher colonic secondary bile acids, lower colonic short-chain fatty acid quantities and

  9. Changing Fatherhood: An Exploratory Qualitative Study with African and African Caribbean Men in England

    Science.gov (United States)

    Williams, Robert; Hewison, Alistair; Wildman, Stuart; Roskell, Carolyn

    2013-01-01

    This paper presents findings from a qualitative study undertaken with 46 African and African Caribbean men exploring their experiences of fatherhood. Data analysis was informed by Connell's theoretical work on changing gender relations. Findings indicate that fathers' lives were mediated by masculinities, racism, gender, migration and…

  10. A SNP test to identify Africanized honeybees via proportion of 'African' ancestry.

    Science.gov (United States)

    Chapman, Nadine C; Harpur, Brock A; Lim, Julianne; Rinderer, Thomas E; Allsopp, Michael H; Zayed, Amro; Oldroyd, Benjamin P

    2015-11-01

    The honeybee, Apis mellifera, is the world's most important pollinator and is ubiquitous in most agricultural ecosystems. Four major evolutionary lineages and at least 24 subspecies are recognized. Commercial populations are mainly derived from subspecies originating in Europe (75-95%). The Africanized honeybee is a New World hybrid of A. m. scutellata from Africa and European subspecies, with the African component making up 50-90% of the genome. Africanized honeybees are considered undesirable for bee-keeping in most countries, due to their extreme defensiveness and poor honey production. The international trade in honeybees is restricted, due in part to bans on the importation of queens (and semen) from countries where Africanized honeybees are extant. Some desirable strains from the United States of America that have been bred for traits such as resistance to the mite Varroa destructor are unfortunately excluded from export to countries such as Australia due to the presence of Africanized honeybees in the USA. This study shows that a panel of 95 single nucleotide polymorphisms, chosen to differentiate between the African, Eastern European and Western European lineages, can detect Africanized honeybees with a high degree of confidence via ancestry assignment. Our panel therefore offers a valuable tool to mitigate the risks of spreading Africanized honeybees across the globe and may enable the resumption of queen and bee semen imports from the Americas. PMID:25846634

  11. African Self-Consciousness and Health-Promoting Behaviors among African American College Students.

    Science.gov (United States)

    Thompson, Shawn N.; Chambers, John W., Jr.

    2000-01-01

    Investigated three models of relationships between African self-consciousness, health consciousness, and health-promoting behaviors among African American college students. The models included the mediator model, moderator model, and independent model. Surveys of 80 students supported the independent model, suggesting that African…

  12. African American Pastors' Beliefs and Actions Regarding Childhood Incest in the African American Community

    Science.gov (United States)

    Wells, Tesia Denis

    2012-01-01

    This quantitative study sought to explore African American pastors' beliefs and actions regarding childhood incest in the African American community and their decisions to inform the proper authorities. This exploratory study was developed in order to draw both public and academic attention to the understudied phenomenon of childhood incest…

  13. Functional Diversification within a Predatory Species Flock

    Science.gov (United States)

    Burress, Edward D.; Duarte, Alejandro; Serra, Wilson S.; Loueiro, Marcelo; Gangloff, Michael M.; Siefferman, Lynn

    2013-01-01

    Ecological speciation is well-known from adaptive radiations in cichlid fishes inhabiting lentic ecosystems throughout the African rift valley and Central America. Here, we investigate the ecological and morphological diversification of a recently discovered lotic predatory Neotropical cichlid species flock in subtropical South America. We document morphological and functional diversification using geometric morphometrics, stable C and N isotopes, stomach contents and character evolution. This species flock displays species-specific diets and skull and pharyngeal jaw morphology. Moreover, this lineage appears to have independently evolved away from piscivory multiple times and derived forms are highly specialized morphologically and functionally relative to ancestral states. Ecological speciation played a fundamental role in this radiation and our data reveal novel conditions of ecological speciation including a species flock that evolved: 1) in a piscivorous lineage, 2) under lotic conditions and 3) with pronounced morphological novelties, including hypertrophied lips that appear to have evolved rapidly. PMID:24278349

  14. Histological review of skin cancers in African Albinos: a 10-year retrospective review

    International Nuclear Information System (INIS)

    Skin cancer is rare among Africans and albinism is an established risk for skin cancer in this population. Ultraviolet radiation is highest at the equator and African albinos living close to the equator have the highest risk of developing skin cancers. This was a retrospective study that involved histological review of all specimens with skin cancers from African albinos submitted to The Regional Dermatology Training Center in Moshi, Tanzania from 2002 to 2011. A total of 134 biopsies from 86 patients with a male to female ratio of 1:1 were reviewed. Head and neck was the commonest (n = 75, 56.0%) site affected by skin cancers. Squamous cell carcinoma (SCC) was more common than basal cell carcinoma (BCC) with a ratio of 1.2:1. Only one Acral lentiginous melanoma was reported. Majority (55.6%) of SCC were well differentiated while nodular BCC (75%) was the most common type of BCC. Squamous cell carcinoma is more common than basal cell carcinoma in African albinos

  15. 77 FR 37886 - Notice of Intent To Obtain Information Regarding Organizations Who Are Assisting African...

    Science.gov (United States)

    2012-06-25

    ... African Governments To Increase Healthcare Institution Capacity To Maintain Complex Medical Equipment..., which are currently helping African government hospitals, clinics, laboratories, and other African... involved in enhancing the long term ability of African government health institutions to maintain...

  16. Radiation carcinogenesis

    International Nuclear Information System (INIS)

    This general discussion is dealt with under the following headings: problems of collecting information (epidemiology, experimental animal studies), the temporal stages of radiation action (physical and chemical effects and cellular response), human cancer, radiation dose and risk, epidemiology and dose-response relationships, cellular and molecular processes (cell inactivation, chromosome damage and cell mutation, radiation transformation, virus and oncogene activation, free radical aspects of radiation carcinogenesis, interaction of radiation and chemical carcinogens. (U.K.)

  17. Africans and Black Americans in the United States: Social Distance and Differential Acculturation.

    Science.gov (United States)

    Emoungu, Paul-Albert

    1992-01-01

    Presents an exploratory examination of the causes of social distance characterizing the association between Africans and African Americans. African American's perceptions about Africa and Africans are assessed through anecdotes and impressions, and thoughts and criticisms of Africans about African Americans are considered. A social science…

  18. The phylogeny of cobras inferred from mitochondrial DNA sequences: evolution of venom spitting and the phylogeography of the African spitting cobras (Serpentes: Elapidae: Naja nigricollis complex).

    Science.gov (United States)

    Wüster, Wolfgang; Crookes, Steven; Ineich, Ivan; Mané, Youssouph; Pook, Catharine E; Trape, Jean-François; Broadley, Donald G

    2007-11-01

    We use phylogenetic analysis of 1333 bp of mitochondrial DNA sequence to investigate the phylogeny and historical biogeography of the cobra-like elapid snakes, with special reference to the evolution of spitting and the phylogeography of the African spitting cobras, a radiation widespread in open vegetational formations throughout sub-Saharan Africa. Our results suggest that spitting adaptations appear to have evolved three times in cobras, but alternative scenarios cannot be rejected. The Asiatic Naja are monophyletic and originate from a single colonization of Asia from Africa. The radiation of the African spitting Naja appears to date back to the early Miocene and many speciation events in the group predate the Pliocene expansion of grasslands and the radiation of large grazing mammals in Africa. The cladogenic events in this complex appear to have been triggered by both ecological changes and tectonic events associated with the formation and expansion of the African Rift Valley. Taxonomically, our data confirm the inclusion of Boulengerina and Paranaja within Naja, and reveal a clade of African rainforest cobras including N. melanoleuca, Paranaja multifasciata and Boulengerina that constitutes the sister clade of the African open-formation non-spitting cobras. Naja nigricollis is polyphyletic, and we therefore recognize N. nigricincta as a separate species, more closely related to N. ashei and N. mossambica than to N. nigricollis. PMID:17870616

  19. Afro-Americans and Early Pan-Africanism

    Science.gov (United States)

    Contee, Clarence G.

    1970-01-01

    History of the Pan-African movement, the roles of W.E.B.Du Bois and Marcus Garvey in the movement activities, and the shift to African based leadership of the movement in the 1940's are discussed. (KG)

  20. What about African Americans and High Blood Pressure?

    Science.gov (United States)

    ANSWERS by heart Lifestyle + Risk Reduction High Blood Pressure What About African Americans and High Blood Pressure? The prevalence of high blood pressure in African Americans is among the highest in ...